Do you have stats for which accounts are downloading, and which files?
The worst-case thought I have is someone purchased it once on a burner itch.io account, and is passing the account around itself for redistribution. There are other, less hijack-prone ways to pirate, so it seems pretty unlikely to me, but if you have access to the data you can probably test against some hypotheses like,
- Is one person suddenly sharing their account with others?
- (Data that would support this hypothesis: Same account downloading lots of times from different IPs)
- Is one person just downloading a bunch of times for some weird reason, e.g. attempting to modify the files without creating a backup?
- (Data that would support this hypothesis: Same account downloading lots of times from the same IP)
- Is there some new, popular itch.io client we haven't heard of, that's managing people's downloads?
- (Data that would support this hypothesis: Many accounts downloading once each, also finding the existence of such a client)
But if you don't have the data, the above is moot. Sorry if I'm leading you down an incorrect rabbit hole!