Don't take my word for it, but as far as I know MP3 (not talking about extensions that are still under patent) expired last year (or possibly earlier than that) Which to my understanding means that, if you use the first version of mp3, you are free to do so. If on the other hand you use mp3 pro functionality and more, you would still need a license. I guess he should have asked about which version is expired. But something tells me they would not willingly tell that, or even blatantly lie about it (aka play 'ignorant') But still.. I dug up an old list that is quite interesting. It shows all patents surrounding mp3 will have expired in 2017. As far as I understand it anyway.
Here it is:
http://www.tunequest.org/a-big-list-of-mp3-patents/20070226/
Please feel free to correct me if you find some mistakes, errors etc.. that I have said
Best of luck.
/Mike