Comment by johnfernow

Actually, making it unavailable wouldn't even solve the problem, as once you purchase a game, even if it is no longer for sale on Steam, you can still redownload it, including to new devices.

So if you've ever released a Unity game (even if it hasn't been updated in years), even if you delist your game from the store today, presumably you could still get charged if people who already own your game reinstall it.

I'm not a lawyer, but I really don't see how that'd hold up in court — you created a product under different terms years ago, and now your product, which isn't even for sale, can be charged for something that your business has no control over. Even if the ToS says Unity reserves the right to change their fees, I don't see how that can apply to products that aren't even being sold anymore.