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 test application covers all primary school students. Application; It consists of three sections: beginner, intermediate and advanced level, each section includes 30 pieces, 90 pieces in total, 5 questions for each piece, and 450 questions in total. When the questions of the pieces are answered correctly, the button of the test turns green so you don't have to keep track of whether your child has solved the test, but your child knows which test he or she has done.