Firstly try restoring purchases
This is done by going to
1.Settings
2.Scroll to near the bottom
3.Click App Purchases
4.Restore Purchases
If it says unlocked and a ✔️
That should be all you need
If you want to try creating a backup and deleting and reinstalling the app try the following:
1.Go to settings
2.Create Full Backup
3.Save to Desktop or your preferred location
Then if you want to try deleting and reinstalling the app you can
To restore you back up
1.Settings
2.Restore Backup
3.Select your backup file from where you saved it (Desktop etc)
4.Press Yes on the pop up alert to restore