There are two ways to access the full version of PDF Reader Pro:
1. Open the app and click Upgrade on the sidebar.
2. Then a comparision table between free and pro version pops up, and there are three plans you can choose: 3-Months, 6-Months and One-time Purchase. Choose the best plan for yourself.
3. If you cannot run the full version after the purchase, please login your Microsoft Account and check your Order History whether you have purchased inside the app.
Note: please make sure that the account you have logged in is the same with the one that you purchse PDF Reader Pro.
If you directly purchase the paid version, PDF Reader Pro - Comment, Edit, Convert, Fill & Sign, you just need to login your account and download and install from Microsoft Store.