Many friends are asking about how to convert M4P files to MP3.

The short answer is that it is not possbile because M4P files are usually protected by DRM technology.

Also it could be illegal to operate such conversion!

Anyway there is a workaround (but remember: you could be breaching the law using this workaround, so it's better you read carefully the license of the M4P files you get). The workaround is pretty easy: use the software that can read and play M4P tracks to burn a AUDIO CD and then use a CD Ripper to extract those tracks to MP3.