What constitutes a successful internship?

So I have about a month left and for the most part it's been a really good experience, personally. I've worked on some major brands, a big pitch (some of my work is in testing for it right now), I'm starting to make some money that will stay in my bank account for more than a few days and I've gotten a really good feel for how this agency operates. Yet, if asked whether or not I think they would offer me a job after this, I'd have to say I really don't know. I don't really know if I've done anything that's job offer worthy. I don't know if I've contributed anything to the agency that another art director couldn't. I don't really know if I've proved myself enough to be remembered by, reffered by or praised by anyone here in the future. At least not any more than the other art directors or some of the other interns. It makes me wonder, what is a good internship? Is it better if you have personally gained from it? Or is it better if the agency and the people you worked for gained from it? I'm starting to think it's the latter.