To use NoteAI on another device, install the app and sign in using the same NoteAI account and the same login method you originally used.
For example, if you originally signed in with Apple, use the same Apple ID. If you used Google, use the same Google account.
Using a different login method may open a different NoteAI account. If your Pro access does not appear on the new device, make sure the correct store account is active and try Restore Purchase from Settings when applicable.