.M4P File Extension
File TypeiTunes Music Store Audio File
File format categories include Binary, Text, XML, and Zip. The format of this file type has not been determined.
What is an M4P file?
In order to play a protected M4P file, you must authorize your computer using Apple iTunes. This is done by entering a username and password for the account that downloaded the file. Up to five computers can be authorized with the same account.