diff --git a/admin/internal/api/checkout.go b/admin/internal/api/checkout.go
index ce6f4f6..9e8999d 100644
--- a/admin/internal/api/checkout.go
+++ b/admin/internal/api/checkout.go
@@ -1,7 +1,9 @@
 package api
 
 import (
+	"context"
 	"fmt"
+	"log"
 	"net/http"
 	"strings"
 	"time"
@@ -246,9 +248,10 @@ func claimPlaceholderLink(c *gin.Context) {
 	if _, err := db.Admin("admin_instances").UpdateOne(ctx,
 		bson.M{"instance_id": placeholderID},
 		bson.M{"$set": bson.M{
-			"instance_id": body.InstanceID,
-			"status":      models.StatusActive,
-			"placeholder": false,
+			"instance_id":                body.InstanceID,
+			"status":                     models.StatusActive,
+			"placeholder":                false,
+			"linked_from_placeholder_id": placeholderID,
 		}}); err != nil {
 		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
 		return
@@ -262,6 +265,15 @@ func claimPlaceholderLink(c *gin.Context) {
 		return
 	}
 
+	// Paddle holds its own copy of custom_data, written at checkout, and it still
+	// names the placeholder. Every later event on this subscription — renewal,
+	// cancellation, an entitlement change — is decoded from it, so leaving it
+	// stale means the next webhook resolves to an id no row carries any more.
+	// Best-effort: the linked_from_placeholder_id alias above is what makes the
+	// webhook path correct whether or not this call lands, and the customer must
+	// not be blocked from linking by an outbound API failure.
+	syncSubscriptionCustomData(ctx, placeholderID, body.InstanceID, inst.AccountID)
+
 	if err := billing.IssueForInstance(ctx, body.InstanceID); err != nil {
 		// The link stuck; issuance did not. The reconciler and a retry recover it,
 		// and the customer is not blocked from linking. Surface it, do not roll back.
@@ -277,6 +289,37 @@ func claimPlaceholderLink(c *gin.Context) {
 	c.JSON(http.StatusOK, gin.H{"instance_id": body.InstanceID})
 }
 
+// syncSubscriptionCustomData rewrites custom_data.instance_id at Paddle for
+// every subscription that named the placeholder, so future events decode to the
+// real UUID. Paddle replaces the whole object on a PATCH, so account_id is sent
+// alongside rather than dropped.
+//
+// Deliberately silent on failure: it is a convergence step, not the correctness
+// boundary — handleSubscription resolves a stale id through the instance row's
+// linked_from_placeholder_id either way.
+func syncSubscriptionCustomData(ctx context.Context, placeholderID, realID, accountID string) {
+	cur, err := db.Admin("subscriptions").Find(ctx, bson.M{"instance_id": realID})
+	if err != nil {
+		log.Printf("claim link %s: read subscriptions: %v", realID, err)
+		return
+	}
+	var subs []models.Subscription
+	if err := cur.All(ctx, &subs); err != nil {
+		log.Printf("claim link %s: decode subscriptions: %v", realID, err)
+		return
+	}
+	for _, s := range subs {
+		if s.PaddleSubscriptionID == "" {
+			continue
+		}
+		if err := paddle.Get().UpdateSubscriptionCustomData(ctx, s.PaddleSubscriptionID,
+			map[string]string{"account_id": accountID, "instance_id": realID}); err != nil {
+			log.Printf("claim link %s: patch custom_data on %s (was %s): %v",
+				realID, s.PaddleSubscriptionID, placeholderID, err)
+		}
+	}
+}
+
 // billingPortal mints a Paddle customer-portal URL. The account must already
 // have a paddle_customer_id, which it learns from its first subscription webhook.
 func billingPortal(c *gin.Context) {
diff --git a/admin/internal/billing/subscription.go b/admin/internal/billing/subscription.go
index bea2abc..9e2567c 100644
--- a/admin/internal/billing/subscription.go
+++ b/admin/internal/billing/subscription.go
@@ -2,6 +2,7 @@ package billing
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"time"
 
@@ -14,6 +15,7 @@ import (
 	"gitea.hostxtra.co.uk/mrhid6/vantage/shared/license"
 	"github.com/google/uuid"
 	"go.mongodb.org/mongo-driver/v2/bson"
+	"go.mongodb.org/mongo-driver/v2/mongo"
 	"go.mongodb.org/mongo-driver/v2/mongo/options"
 )
 
@@ -67,9 +69,21 @@ func handleSubscription(ctx context.Context, ev Event) error {
 		return fmt.Errorf("resolve items for subscription %s: %w", d.ID, err)
 	}
 
+	// Resolve BEFORE recording. A self-hosted subscription's custom_data is
+	// written at checkout and names the placeholder; the claim rewrote the
+	// instance's identity to the install's real UUID and patched Paddle, but that
+	// patch is best-effort and any event already in flight still carries the old
+	// id. Writing it straight through would revert the linked subscription row and
+	// then fail to find the instance, wedging every renewal.
+	instanceID, inst, err := resolveInstance(ctx, d.CustomData.InstanceID)
+	if err != nil {
+		return fmt.Errorf("subscription %s names unknown instance %s: %w",
+			d.ID, d.CustomData.InstanceID, err)
+	}
+
 	sub := models.Subscription{
 		AccountID:            d.CustomData.AccountID,
-		InstanceID:           d.CustomData.InstanceID,
+		InstanceID:           instanceID,
 		PaddleSubscriptionID: d.ID,
 		Tier:                 match.Tier,
 		Term:                 match.Term,
@@ -88,13 +102,6 @@ func handleSubscription(ctx context.Context, ev Event) error {
 			bson.M{"$set": bson.M{"paddle_customer_id": d.CustomerID}})
 	}
 
-	var inst models.Instance
-	if err := db.Admin("admin_instances").FindOne(ctx,
-		bson.M{"instance_id": d.CustomData.InstanceID}).Decode(&inst); err != nil {
-		return fmt.Errorf("subscription %s names unknown instance %s: %w",
-			d.ID, d.CustomData.InstanceID, err)
-	}
-
 	// Placeholders are the payment-first path: the instance does not exist until
 	// this confirmed-payment event. A cloud placeholder is provisioned here and
 	// then issued (first term). A self-hosted placeholder has no UUID to bind to
@@ -116,6 +123,27 @@ func handleSubscription(ctx context.Context, ev Event) error {
 	return promoteAndIssue(ctx, &inst, match, reason)
 }
 
+// resolveInstance finds the instance a webhook's custom_data names, following the
+// placeholder alias when the id is one a self-hosted claim has since replaced.
+// It returns the instance's CURRENT id, which is the only id anything else should
+// be written against.
+func resolveInstance(ctx context.Context, customDataID string) (string, models.Instance, error) {
+	var inst models.Instance
+	err := db.Admin("admin_instances").FindOne(ctx,
+		bson.M{"instance_id": customDataID}).Decode(&inst)
+	if err == nil {
+		return inst.InstanceID, inst, nil
+	}
+	if !errors.Is(err, mongo.ErrNoDocuments) {
+		return "", inst, err
+	}
+	if err := db.Admin("admin_instances").FindOne(ctx,
+		bson.M{"linked_from_placeholder_id": customDataID}).Decode(&inst); err != nil {
+		return "", inst, err
+	}
+	return inst.InstanceID, inst, nil
+}
+
 // promoteAndIssue promotes desired→granted from the resolved match, then signs a
 // licence from granted. This is the only promotion path other than the staff
 // grant, and it exists because a webhook is a confirmed payment.
@@ -280,9 +308,10 @@ func billingEmailFor(ctx context.Context, accountID string) string {
 
 // instanceNameFor is a best-effort display name for an email subject.
 func instanceNameFor(ctx context.Context, instanceID string) string {
-	var inst models.Instance
-	if err := db.Admin("admin_instances").FindOne(ctx,
-		bson.M{"instance_id": instanceID}).Decode(&inst); err != nil || inst.Name == "" {
+	// Alias-aware: a cancellation can name a placeholder id, and "your instance"
+	// in place of the name the customer chose reads like the wrong email.
+	_, inst, err := resolveInstance(ctx, instanceID)
+	if err != nil || inst.Name == "" {
 		return "your instance"
 	}
 	return inst.Name
diff --git a/admin/internal/models/backfill.go b/admin/internal/models/backfill.go
index b150766..50926d4 100644
--- a/admin/internal/models/backfill.go
+++ b/admin/internal/models/backfill.go
@@ -4,6 +4,7 @@ import (
 	"context"
 	"errors"
 	"log"
+	"strings"
 	"time"
 
 	"gitea.hostxtra.co.uk/mrhid6/vantage/admin/internal/db"
@@ -210,6 +211,54 @@ func Backfill(ctx context.Context) error {
 	if err := backfillEntitlements(ctx); err != nil {
 		return err
 	}
+
+	// Pass 6: instances claimed before linked_from_placeholder_id existed have no
+	// alias, and Paddle's custom_data still names the placeholder they were
+	// claimed from — so their next webhook resolves to nothing. The claim wrote an
+	// audit entry naming both ids, which is the only surviving record of the
+	// placeholder, so reconstruct the alias from it.
+	if err := backfillPlaceholderAliases(ctx); err != nil {
+		return err
+	}
+	return nil
+}
+
+// backfillPlaceholderAliases rebuilds linked_from_placeholder_id from the
+// instance.placeholder_linked audit entries. Idempotent by filtering on the
+// absence of the field.
+func backfillPlaceholderAliases(ctx context.Context) error {
+	cur, err := db.Admin("admin_audit").Find(ctx,
+		bson.M{"action": "instance.placeholder_linked"})
+	if err != nil {
+		return err
+	}
+	var entries []AuditEntry
+	if err := cur.All(ctx, &entries); err != nil {
+		return err
+	}
+
+	const prefix = "from placeholder "
+	linked := 0
+	for _, e := range entries {
+		if e.Target == "" || !strings.HasPrefix(e.Detail, prefix) {
+			continue
+		}
+		placeholderID := strings.TrimSpace(strings.TrimPrefix(e.Detail, prefix))
+		if placeholderID == "" || placeholderID == e.Target {
+			continue
+		}
+		res, err := db.Admin("admin_instances").UpdateOne(ctx,
+			bson.M{"instance_id": e.Target,
+				"linked_from_placeholder_id": bson.M{"$exists": false}},
+			bson.M{"$set": bson.M{"linked_from_placeholder_id": placeholderID}})
+		if err != nil {
+			return err
+		}
+		linked += int(res.ModifiedCount)
+	}
+	if linked > 0 {
+		log.Printf("backfill: recovered %d placeholder aliases from the audit log", linked)
+	}
 	return nil
 }
 
diff --git a/admin/internal/models/models.go b/admin/internal/models/models.go
index feec4af..7c4abc1 100644
--- a/admin/internal/models/models.go
+++ b/admin/internal/models/models.go
@@ -147,6 +147,13 @@ type Instance struct {
 	// checkout has something to attach custom_data to, before the customer has
 	// pasted their install's real UUID. Cleared when the instance is linked.
 	Placeholder bool `bson:"placeholder,omitempty" json:"placeholder,omitempty"`
+	// LinkedFromPlaceholderID is the id this row carried while it was a
+	// self-hosted placeholder, kept forever after the claim rewrote InstanceID to
+	// the install's real UUID. Paddle's copy of custom_data still names the
+	// placeholder on any subscription created before the claim (and on any webhook
+	// delivered while the outbound patch was failing), so this is what lets a
+	// later webhook resolve to the right instance instead of erroring as unknown.
+	LinkedFromPlaceholderID string `bson:"linked_from_placeholder_id,omitempty" json:"-"`
 	// PendingOwnerUserID is the customer_user who bought a paid-cloud placeholder,
 	// remembered so the confirmed-payment webhook can provision the instance with
 	// them as owner. Cleared once provisioned. Only ever set on a cloud placeholder.
diff --git a/admin/internal/paddle/client.go b/admin/internal/paddle/client.go
index e133e6c..5ddd1f7 100644
--- a/admin/internal/paddle/client.go
+++ b/admin/internal/paddle/client.go
@@ -25,6 +25,10 @@ type Client interface {
 	// immediately by Paddle. This is the one outbound mutation, used when a
 	// customer changes their server count or features on an existing plan.
 	UpdateSubscriptionItems(ctx context.Context, paddleSubscriptionID string, items []LineItem) error
+	// UpdateSubscriptionCustomData replaces a subscription's custom_data. Used
+	// when a self-hosted placeholder is claimed: the checkout attached the
+	// placeholder id, and every later webhook must name the real install UUID.
+	UpdateSubscriptionCustomData(ctx context.Context, paddleSubscriptionID string, data map[string]string) error
 	// PortalSession returns a customer-portal URL for managing billing.
 	PortalSession(ctx context.Context, paddleCustomerID string) (string, error)
 	// Env is "sandbox" or "production", the same value catalogue price lookups
diff --git a/admin/internal/paddle/http.go b/admin/internal/paddle/http.go
index 2b94371..0bf8985 100644
--- a/admin/internal/paddle/http.go
+++ b/admin/internal/paddle/http.go
@@ -99,6 +99,17 @@ func (c *httpClient) UpdateSubscriptionItems(ctx context.Context, subID string,
 	}, nil)
 }
 
+// UpdateSubscriptionCustomData patches custom_data only. Paddle replaces the
+// whole object, so callers pass every key they want to keep.
+func (c *httpClient) UpdateSubscriptionCustomData(ctx context.Context, subID string, data map[string]string) error {
+	if subID == "" {
+		return fmt.Errorf("paddle: empty subscription id")
+	}
+	return c.do(ctx, http.MethodPatch, "/subscriptions/"+subID, struct {
+		CustomData map[string]string `json:"custom_data"`
+	}{CustomData: data}, nil)
+}
+
 func (c *httpClient) PortalSession(ctx context.Context, customerID string) (string, error) {
 	if customerID == "" {
 		return "", fmt.Errorf("paddle: empty customer id")