Firstly try restoring purchases
This is done by going to
1.Settings
2.Scroll to near the bottom
3.Click App Purchases
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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
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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
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3.Select your backup file from where you saved it (Desktop etc)
4.Press Yes on the pop up alert to restore