A friend and I have been developing an application which will be used as a startup venture. There is a considerable amount of work to be done. We have not set up any legal framework, business not formed yet, however he has walked away and shows little interest. I would like to offer to buy him out and continue to build the business myself. This means buying his half of the application designs, documentation, code, stylesheets etc.
I believe he may be receptive to this but wonder what legal documentation would be required that he cannot return in the future and lay claim to any part of the business?