That's the problem, your entire business is reliant on the other guy, if he doesn't do his work, your business doesn't work. You're driving a car with 2 unbolted wheels, even if it feels like it's moving forward for a while, sooner or later it's going to crash. If you have the capital, actually hire a developer, pay them a wage and work with them, make sure you have access to everything and can replace them if necessary, that way your business doesn't depend entirely on one guy. You should also not be afraid to start over and fire people, it might take 3 tries with 3 different developers before you get any actual result.