Okay, let's see if this makes sense...
You supposedly work for a company, but they're not paying you. That makes you a voluntary contributor at best. Although you're not actually an employee, the company allows you to use their code for a program you're going to release to the public without paying. Although you can use their code, you can't actually release it to anyone. You don't need any money to develop this program, but you're panhandling.
I'm counting at least five red flags right there.
There are certain things I don't want in my food (MSG, meat, HFCS, mercury). By the same token, there are certain things I don't want in software (spyware, DRM, key loggers). A refusal to show source code is just as suspicious as a can of soup that refuses to list its ingredients, especially coming from a shady vendor who I have absolutely no reason to trust. What don't they/you want me to know about their/your product? What's in it that they/you are trying to hide?