I have an old EULA here, but it says:
Quote: "1.2 You are not permitted:
(f) exploit (or permit any other person to exploit) any Game in return for any benefit or consideration, whether financial or otherwise."
I think it's not only about the game being free or not, you should need a commercial license if you make any money of it.
I've seen this question asked (and answered it) a bunch of times. TGC should make a sticky post with what you can and cannot do with a Freeware license (in a clearer way, not too "Lawyer's Language" as the EULA).