Practise on more than one device

Use an account

Create an account and sign in with it on every device: Create or sign in to your account.

This is the surest way to carry both your purchase and your progress everywhere.

It's essential if you use more than one platform. An iPhone has no way of knowing about a purchase made on Google Play, and Google Play has no way of knowing about a purchase made on the App Store. An account is the only thing that connects them.

Without an account

Things may still work if you stay on one platform, but it isn't guaranteed. Even devices from the same maker can be separate: the Mac App Store is technically distinct from the iOS App Store, so a macOS app may not recognise a purchase made on your iPhone.

Either way, be consistent

Use the same account everywhere, or no account anywhere. Don't mix.

Signing in on one device but not another, or signing in with two different accounts, is what causes problems: your purchase ends up attached to whichever account restored it last, leaving your other device without access and your progress unsynced.