Can you be registered as P.R.O. member and be able to sell corporate-music? Or will some customers refuse to buy it because they have no deal with a P.R.O.? Thanks in advance for your tips. 
Hi. Of course we are able to do it and it’s better to be registered.
Here you can read about it: The AJ Community Guide #2 - Performing Rights Organisation Royalties (PRO)
Thank you!
Great question. I was wondering the same thing.