During my internship a few months back, I developed this software for a certain energy company, which interestingly now they are finding quite profitable, and want to extend it to a national level, they have asked me as a favor to come and teach some of the company's developers the main features of the application so they can keep on with the development.
Now of course I don't plan on it, unless some mutual agreement is found during a meeting next week, but the issue is, when I signed up for the internship I don't remember signing any documents saying that anything I developed belonged to them, and if I did I have no documentation of it whatsoever. The software was developed on site, although I was asked to bring my own equipment, so the application was never really developed on any of their computers.
I had no work contract at all, so nothing stating my work belonged to them there either.
I did receive a payment, but that was more symbolical than anything, and since there was no contract there was never any resignation either.
So again, who owns the code?