Yea... this is something you should have talked about on day -1. You can really mess up relationships by not getting the expectations out there and then making sure everyone lives up to them.

I would have a conversation with ownership and see if they want to give you any stock. I would couch it by saying. I'm really glad you let me learn from you, but I think its time for me to either get a job or get some visibility to one here.

I won't start making demands... doesn't sound like you set the expectations in the beginning and that's on you. Don't get mad at them for accepting your "help" paid or not. They might value your contribution very differently than you.