After installation, double click the icons to launch the program. iTunes will be opened with it automatically. The music in your iTunes will be displayed on the main interface of the software.
Click the "Options" button. Then you can enable or disable some settings about "Convert" and "Output" files. Especially you can choose preserving the Metadata information in output MP3 and M4A file.
Find and click on the "Convert" button. Several minutes later, you can get the unprotected MP3 audio files and play them anytime and anywhere.