Please log out and re-login your account
After you pay successfully, if you still can't use the advanced features, please log out of the account and log in again. By the way, tap on your App menu on the top left corner and you will see a crown and the cloud storage is 5GB.
Send us the Apple receipt with the order number
If you succeed in payment, Apple will send you a receipt, or invoice/statement like below. Please do send us the invoice or statement with order number, not the confirmation of subscription. We need the order number to find out your orders and add premium to your account manually.