diff --git a/app/src/main/kotlin/com/google/ai/sample/MainActivity.kt b/app/src/main/kotlin/com/google/ai/sample/MainActivity.kt
index 510bc0a0..0a0a7c93 100644
--- a/app/src/main/kotlin/com/google/ai/sample/MainActivity.kt
+++ b/app/src/main/kotlin/com/google/ai/sample/MainActivity.kt
@@ -657,21 +657,52 @@ class MainActivity : ComponentActivity() {
                     }
                 } else {
                     Log.i(TAG, "queryActiveSubscriptions: User has no active subscription for $subscriptionProductId. Re-evaluating trial logic.")
+                    // --- START: MODIFICATION ---
+                    if (TrialManager.isPurchased(this@MainActivity)) {
+                        Log.w(TAG, "queryActiveSubscriptions: No active subscription found by Google Play Billing, but app was previously marked as purchased. Clearing purchase mark.")
+                        TrialManager.clearPurchaseMark(this@MainActivity)
+                    }
+                    // --- END: MODIFICATION ---
                     if (TrialManager.getTrialState(this, null) != TrialManager.TrialState.PURCHASED) {
                         Log.d(TAG, "queryActiveSubscriptions: No active sub, and TrialManager confirms not purchased. Re-evaluating trial state and starting service if needed.")
                         updateTrialState(TrialManager.getTrialState(this, null))
+                        // --- START: MODIFICATION ---
+                        if (currentTrialState == TrialManager.TrialState.EXPIRED_INTERNET_TIME_CONFIRMED) {
+                            Log.i(TAG, "queryActiveSubscriptions: Subscription deactivated (no active sub and trial expired). Showing Toast.")
+                            Toast.makeText(this@MainActivity, "Subscription is deactivated", Toast.LENGTH_LONG).show()
+                        }
+                        // --- END: MODIFICATION ---
                         startTrialServiceIfNeeded()
                     } else {
                          Log.w(TAG, "queryActiveSubscriptions: No active sub from Google, but TrialManager says PURCHASED. This could be due to restored SharedPreferences without active subscription. Re-evaluating trial logic based on no internet time.")
-                         updateTrialState(TrialManager.getTrialState(this, null)) 
+                         updateTrialState(TrialManager.getTrialState(this, null))
+                         // --- START: MODIFICATION ---
+                         if (currentTrialState == TrialManager.TrialState.EXPIRED_INTERNET_TIME_CONFIRMED) {
+                            Log.i(TAG, "queryActiveSubscriptions: Subscription deactivated (no active sub, was purchased, now trial expired). Showing Toast.")
+                            Toast.makeText(this@MainActivity, "Subscription is deactivated", Toast.LENGTH_LONG).show()
+                         }
+                         // --- END: MODIFICATION ---
                          startTrialServiceIfNeeded()
                     }
                 }
             } else {
                 Log.e(TAG, "Failed to query active subscriptions: ${billingResult.debugMessage}")
                 Log.d(TAG, "queryActiveSubscriptions: Query failed. Re-evaluating trial state based on no internet time and starting service if needed.")
+                // --- START: MODIFICATION ---
+                // It's important to also check/clear purchase mark here if query fails but app thought it was purchased
+                if (TrialManager.isPurchased(this@MainActivity)) {
+                    Log.w(TAG, "queryActiveSubscriptions: Failed to query active subscriptions, but app was previously marked as purchased. Clearing purchase mark.")
+                    TrialManager.clearPurchaseMark(this@MainActivity)
+                }
+                // --- END: MODIFICATION ---
                 if (TrialManager.getTrialState(this, null) != TrialManager.TrialState.PURCHASED) {
                     updateTrialState(TrialManager.getTrialState(this, null))
+                    // --- START: MODIFICATION ---
+                    if (currentTrialState == TrialManager.TrialState.EXPIRED_INTERNET_TIME_CONFIRMED) {
+                        Log.i(TAG, "queryActiveSubscriptions: Subscription deactivated (query failed, trial expired). Showing Toast.")
+                        Toast.makeText(this@MainActivity, "Subscription is deactivated", Toast.LENGTH_LONG).show()
+                    }
+                    // --- END: MODIFICATION ---
                     startTrialServiceIfNeeded()
                 }
             }
diff --git a/app/src/main/kotlin/com/google/ai/sample/TrialManager.kt b/app/src/main/kotlin/com/google/ai/sample/TrialManager.kt
index e1ddd9d6..bcc54787 100644
--- a/app/src/main/kotlin/com/google/ai/sample/TrialManager.kt
+++ b/app/src/main/kotlin/com/google/ai/sample/TrialManager.kt
@@ -235,7 +235,7 @@ object TrialManager {
         Log.i(TAG, "App marked as purchased. Trial data (including obfuscated end time and confirmed expired flag) cleared. Purchase status stored in KEY_FEATURE_ACCESS_FLAG.")
     }
 
-    private fun isPurchased(context: Context): Boolean {
+    internal fun isPurchased(context: Context): Boolean {
         // Comment for future AI: KEY_FEATURE_ACCESS_FLAG indicates the app has been purchased.
         Log.d(TAG, "isPurchased called, checking KEY_FEATURE_ACCESS_FLAG")
         val purchased = getSharedPreferences(context).getBoolean(KEY_FEATURE_ACCESS_FLAG, false)
@@ -243,6 +243,21 @@ object TrialManager {
         return purchased
     }
 
+    fun clearPurchaseMark(context: Context) {
+        Log.d(TAG, "clearPurchaseMark called")
+        val editor = getSharedPreferences(context).edit()
+        // Comment for future AI: KEY_FEATURE_ACCESS_FLAG is set to false to indicate the feature is no longer accessed via purchase.
+        Log.d(TAG, "Setting KEY_FEATURE_ACCESS_FLAG to false")
+        editor.putBoolean(KEY_FEATURE_ACCESS_FLAG, false)
+        // Comment for future AI: KEY_INITIAL_SETUP_FLAG is reset to true to allow trial re-evaluation.
+        Log.d(TAG, "Setting KEY_INITIAL_SETUP_FLAG to true")
+        editor.putBoolean(KEY_INITIAL_SETUP_FLAG, true)
+        // IMPORTANT: KEY_CFG_TS (obfuscated trial end time) and KEY_CFG_ST (obfuscated confirmed expired flag)
+        // are intentionally NOT cleared here. The original trial period might still be relevant.
+        editor.apply()
+        Log.i(TAG, "Purchase mark cleared. Feature access flag set to false, initial setup flag reset to true. Trial end time and expired flag preserved.")
+    }
+
     fun initializeTrialStateFlagsIfNecessary(context: Context) {
         Log.d(TAG, "initializeTrialStateFlagsIfNecessary called")
         val prefs = getSharedPreferences(context)