We have found 2 software records in our database eligible for .flac to .m4p file format conversion.
In theory, flac to m4p conversion is possible, because it's pretty much just turning FLAC audio files to iTunes specific variant of MP4 format that often features DRM protection.
You might as well just convert your flac files to mp4 (aac audio track) and rename the extension to m4p, if you, for whatever reason, need this.
Some audio tools support M4P files and can play or export them, but we are not aware of any utility that would be explicitly designed to produce these files from other audio content.
A music library management program - renamed to Helium (version 12) and replaced in 2016
FLAC
Files with flac extension are used for audio files compressed with the FLAC, aka Free Lossless Audio Codec. FLAC files do not lose any quality with their compression as MP3 do, but they are generally larger. Most modern media players support playback of FLAC files.
M4P
An m4p file extension is associated with the proprietary version of AAC (advanced audio coding) for the MP4 file format with Digital Rights Management developed by Apple, for the use in music files downloaded from their iTunes Music Store.