Recover4all does not install any files on your computer, because saving files to your computer can possibly overwrite your deleted files. So there is no need to uninstall the program.
If you purchase the program, you will have the option to save your registration key in the Windows registry, so that you don`t need to enter it each time you run the program. For your information, the key is:
HKEY_LOCAL_MACHINE - SOFTWARE - Advanced Utilities