[Autumn]

How about a login message that appears for every warning you've ever gotten, along with a date. That way you don't miss a warning, and you're constantly reminded not to break the rules every time you log in.

Received warning 8/2/18: "[insert description of warning]"

Sounds intrusive and is per key-to-key basis, rather than for the player, so overall it'd be ineffective to the many players who have more than 2 or 3 keys.