If you've changed your device, you can re-activate your premium account on the new device you're using.
If you didn't switch between platforms:
1. Launch Hobi
2. From the top menu, select Settings
3. Tap "Restore Purchases" and wait for about a minute.
4. That's it! Enjoy Hobi.
If you did switch between platforms (iOS -> Android or Android -> iOS):
In your old device:
1. Launch Hobi.
2. From the top menu, select Settings.
3. Tap "Restore Purchases" and wait for about a minute.
4. From the top menu, select Sign In and use your Google account to sign in.
Next, in your new device:
1. Launch Hobi
2. From the top menu, select Sign In and use the same Google account you've used on step 2.
3. All done!