I have to reenter my code each time I open MP3 Magic, after code entering, it says valid, but next time I open I have to reenter it again.
This happens because you are using a modern operating system and you're not running the application as Administrator. When apps are installed on the system partition and launched with a normal user, Windows stores all the changes in temporary files. Therefore, right click the icon of MP3 Magic and choose Run as Administrator. This will give the app permissions to store the necessary registration data in files or in the registry area.