Power Planner is mostly a free app, however for $2.99 USD, you can unlock a few additional features.
The purchase is a one-time, lifetime purchase, and it also syncs across your account, so if you purchase on Android, you'll also unlock premium on Windows and iOS, or vice versa!
The free version is limited to...
- 1 semester
- 5 grades per class
- 1 repeating bulk entry of a task/event
- 1 photo attachment per item