Don't try to count, just establish an upper bound. "I have 1000 servers using this shared key, and they each open at most 1000000 connections per second, so as

Don't try to count, just establish an upper bound. "I have 1000 servers using this shared key, and they each open at most 1000000 connections per second, so as long as I change the key in the next 500 years I should be fine."