Hi Bill.

Re paying for a demo. It would all depend on what agreement you have with the studio. I pay for studio time that includes mixing and mastering and what I take away is mine to do with as I want. Any musicians who I use are paid on a work for hire basis and their contribution becomes my property to do with what I want. I have worked for studios on work for hire projects where my vocals are now the property of the songwriter who paid for the studio and my time. It is the preferred system. Sometimes as we are all pals we will work free for each other and the favours returned as required. It is a neat system but relies on mutual trust.

Things should always be spelled out before going into a studio or hiring musicians so that there are no disputes afterwards.

It may be worth while checking with the studio you used exactly what you can do with the demo they produced.