Had an audience of three at a club in Philadelphia. Did one set from the stage then went to their table for the other two. One of the guys played harp (harmonica) and another played rhythm on chair. Last set was all of us singing, doing harmonies, whatever. They cam back the following night when the club was packed. I brought them in as my guests, just by way of saying thanks.

Pro means you do what you have accepted to do, and you then have the right to be paid in full.