How to restore existing in-app upgrades after a reinstall

All downloads and purchases from the Microsoft Store are linked to your Microsoft account. You do not need to pay again for existing purchases as long as you are using the same Microsoft account. (this is very important)

Your in-app upgrades should be restored automatically if you are already logged in. If you do not see your upgrades:

check that you are logged into the same Microsoft account you originally used to make the purchase
if you switch between different accounts on the same device, reboot your device after logging into the correct account
if you had reinstalled the app under a different account, it may help to delete and reinstall after you switch to the correct account
review your account purchase details by going to https://account.microsoft.com > “Payments & Billings” > “Order history”
This app is sold exclusively on the Microsoft Store. Microsoft handles all purchases and installs.

More information available at
https://support.microsoft.com/help/4000641