This app does not do anything by itself. It has no user interface and no icon will appear in the launcher. When it is installed, Morse Code Trainer (https://play.google.com/store/apps/details?id=com.profittlich.android.morsecodetrainer) will not display ads.
Before purchasing this app, try out Morse Code Trainer to see if it suits your needs.
If you experience any problems, please contact me, so I can resolve them.