Apple's version of the app includes a "restore purchases" function to assist with pushing your purchases to your account in the event of a crash.
Starting from the main screen, we tap on the 'options' icon in the top right.
This will open the options menu, from here we tap on 'Account" in the lower left:
On the final screen, a "Restore Purchases" icon can be tapped on on the bottom:
This function should push any purchases to your account that have not been added.
If you are still experiencing difficulty with your purchase, please contact our support team here!