The fee for the paid application is one time. It is not monthly or annual. There is no time limit, you use it unless you delete it. You may need to delete the free app before installing the paid app. There may be conflicts because there are similar programs. If there is a problem with the download, Google play will refund the fee. To pay the fee from your line, your line must be open for shopping. Otherwise, your payment will be rejected.

The app has all 4th Grade math topics. In practice, the test is less and most of the activities are intended to be deliberate by entering the results with the keyboard. The four operations and Measure conversions (time-length-liquid-weight) are unlimited. There are 10 questions in each section, when 10 questions are solved correctly, the button color changes and is saved only on your phone. The correct number appears for unlimited transactions and is saved only on your phone. It can be done in the form of a competition with friends.