On iOS, you can transfer purchased Notes Writer unlock upgrade from one iOS device to another as long as you use the same Apple ID and iCloud account and you've installed the same version of the app.
1. Open Notes Writer Free version
2. Tap the "..." button in the top toolbar and choose "Upgrade to Full Version" opition.
3. There is a button named "Restore purchases", tap on it to restore your purchase.
4. Log in to your Apple ID
5. It can take a few minutes to restore your purchase.
Notes Writer Team