I need to know if m4a format is copyrighted like mp3 is and if I can just use m4a files in my game without the world coming to an end. Thanks.

If I recall correctly, M4A isn't encumbered by the sort of licensing restrictions that MP3 is. However, note that you don't need to do anything special to distribute MP3s, either; it's only encoders and decoders that have to pay a licensing fee. If you're using Apple-provided APIs to decode MP3s, you're safe, because Apple themselves have already taken care of the license for you.