Coupons are the closest things we have to key management --
They are also quite short for game keys and the right programmer could just iterate through them in no time.
The temporary workaround to a real key mgmt system would be to optionally generate longer codes that are less hackable when you are generating 1000s at a time.
Our codes are 3-4-3 format alphanumerics (ex: "abc-1234-xyz"), and we do not allow clients to call at a high rate (they get throttled - or blocked, if it's determined that they are attempting something like a DoS attack). So, even if they were to make the maximum number of calls per minute, and assuming you've generated hundreds of thousands of keys, the odds of them finding a valid one in their lifetime is going to be fairly remote.
Ah I didn't know about the throttling - that makes me feel more-at-ease.
