diff --git a/adapters/lastfm/agent.go b/adapters/lastfm/agent.go
index eb8f3d36e..7a1125167 100644
--- a/adapters/lastfm/agent.go
+++ b/adapters/lastfm/agent.go
@@ -370,11 +370,26 @@ func (l *lastfmAgent) NowPlaying(ctx context.Context, userId string, track *mode
 	})
 	if err != nil {
 		log.Warn(ctx, "Last.fm client.updateNowPlaying returned error", "track", track.Title, err)
+		l.dropSessionKeyIfInvalid(ctx, userId, err)
 		return errors.Join(err, scrobbler.ErrUnrecoverable)
 	}
 	return nil
 }
 
+// dropSessionKeyIfInvalid discards a session key that Last.fm has rejected, so the
+// account stops reporting as linked and the user is prompted to re-authenticate
+// instead of scrobbles failing silently.
+func (l *lastfmAgent) dropSessionKeyIfInvalid(ctx context.Context, userId string, err error) {
+	var lfErr *lastFMError
+	if !errors.As(err, &lfErr) || lfErr.Code != errorInvalidSessionKey {
+		return
+	}
+	log.Warn(ctx, "Last.fm session key was rejected, unlinking account", "userId", userId, err)
+	if delErr := l.sessionKeys.Delete(ctx, userId); delErr != nil {
+		log.Error(ctx, "Could not delete rejected Last.fm session key", "userId", userId, delErr)
+	}
+}
+
 func (l *lastfmAgent) Scrobble(ctx context.Context, userId string, s scrobbler.Scrobble) error {
 	sk, err := l.sessionKeys.Get(ctx, userId)
 	if err != nil || sk == "" {
@@ -407,6 +422,7 @@ func (l *lastfmAgent) Scrobble(ctx context.Context, userId string, s scrobbler.S
 	if lfErr.Code == 11 || lfErr.Code == 16 {
 		return errors.Join(err, scrobbler.ErrRetryLater)
 	}
+	l.dropSessionKeyIfInvalid(ctx, userId, err)
 	return errors.Join(err, scrobbler.ErrUnrecoverable)
 }
 
diff --git a/adapters/lastfm/agent_test.go b/adapters/lastfm/agent_test.go
index 7e4e29294..b9d178905 100644
--- a/adapters/lastfm/agent_test.go
+++ b/adapters/lastfm/agent_test.go
@@ -24,6 +24,7 @@ import (
 const (
 	lastfmError3 = `{"error":3,"message":"Invalid Method - No method with that name in this package","links":[]}`
 	lastfmError6 = `{"error":6,"message":"The artist you supplied could not be found","links":[]}`
+	lastfmError9 = `{"error":9,"message":"Invalid session key - Please re-authenticate","links":[]}`
 )
 
 var _ = Describe("lastfmAgent", func() {
@@ -516,6 +517,32 @@ var _ = Describe("lastfmAgent", func() {
 				err := agent.Scrobble(ctx, "user-1", scrobbler.Scrobble{MediaFile: *track, TimeStamp: time.Now()})
 				Expect(err).To(MatchError(scrobbler.ErrUnrecoverable))
 			})
+
+			It("unlinks the account when the session key is rejected", func() {
+				httpClient.Res = http.Response{
+					Body:       io.NopCloser(bytes.NewBufferString(lastfmError9)),
+					StatusCode: 403,
+				}
+
+				err := agent.Scrobble(ctx, "user-1", scrobbler.Scrobble{MediaFile: *track, TimeStamp: time.Now()})
+
+				Expect(err).To(MatchError(scrobbler.ErrUnrecoverable))
+				Expect(agent.IsAuthorized(ctx, "user-1")).To(BeFalse())
+			})
+		})
+
+		Describe("session key rejected during NowPlaying", func() {
+			It("unlinks the account", func() {
+				httpClient.Res = http.Response{
+					Body:       io.NopCloser(bytes.NewBufferString(lastfmError9)),
+					StatusCode: 403,
+				}
+
+				err := agent.NowPlaying(ctx, "user-1", track, 0)
+
+				Expect(err).To(HaveOccurred())
+				Expect(agent.IsAuthorized(ctx, "user-1")).To(BeFalse())
+			})
 		})
 	})
 
diff --git a/adapters/lastfm/client.go b/adapters/lastfm/client.go
index 726df1360..c14ce7340 100644
--- a/adapters/lastfm/client.go
+++ b/adapters/lastfm/client.go
@@ -19,6 +19,9 @@ import (
 
 const (
 	apiBaseUrl = "https://ws.audioscrobbler.com/2.0/"
+
+	// https://www.last.fm/api/errorcodes
+	errorInvalidSessionKey = 9
 )
 
 type lastFMError struct {