I see that you have added a fully functional ITUNESACCOUNT tag edit. Great to be able to edit the Apple Store ID email address in Mp3tag v2.64 (nice). I was editing some of my iTunes albums that are in .m4a format with Mp3tag v2.64....
I noticed that you don't have an add iTunes "Purchased By" action programmed into Mp3tag v2.64. There also is no action coded into Mp3tag v2.64 to edit iTunes "Purchased By" for albums with a pre-existing iTunes "Purchased By" tag. So, if I want to edit the "Purchased By" tag in an album purchased on the iTunes Store, I can't edit the tag with your application. So, I had to manually recode this detail in each .m4a file of my albums one audio file at a time. You have to be really patient to do this for even 2 albums.
I am trying to help you add this feature/action to Mp3tag v2.64 or Mp3tag v2.64, but not sure what you are using to code Mp3tag v2.64. Anyway, I had to open each .m4a file with a Hex Editor, and edit the "Purchased By" tag manually. I know what address this information resides at. Just give me credit for this in the next release, and we are cool. They call me, mU$!c inc.
I was reading through the code of an .m4a file , and it looks like you just need to add several lines of code to add this tag to a file that was ripped from a physical CD or a .m4a file that as not an iTunes purchase. These lines of code are generically coded into the beginning of all audio files that are purchased from the iTunes Store.
CONTACT ME ASAP! Thanks