If you set up your new iPhone with the same Apple ID, your Gust subscription should restore automatically when you open the app and sign in.
If Gust doesn't recognize your subscription
Open Gust.
Sign in with the same email you originally signed up with (Apple, Google, or email login — whichever you used).
Go to Profile → Settings.
Tap Restore Purchases.
This forces Gust to re-check your Apple subscription and unlock the app.
Common reasons restore doesn't work
Different Apple ID on the new device. Restore only works for the Apple ID that bought the subscription. Check Settings → [your name] → Media & Purchases.
Different Gust account. Your Gust account (Apple/Google/email) must also match. If you signed up with Apple before and now signed in with email, you'll be on a different account.
No internet connection. Connect to Wi-Fi or cellular and try again.
Lifetime plan on a new device
Lifetime works the same way — sign in with the same Apple ID and Gust account, tap Restore Purchases.
Still need help?
If restore still doesn't unlock the app, tap Contact Support in Settings and send your Apple ID email plus the email of your Gust account.