If I get a supporter account later on, or if someone has a supporter account, let's it expire, then gets one again several months later, will the collected flags for friendlies played in other countries be remembered?

Thanks

After your support account expiration everything stays in database, flags, book entries, tactics, cheerleaders, even finacial fines. When you renew supporter account, you'll get everything back, so don't worry.

Nice use of words. Point is, you don't loose anything.

We don't have such a small fines as in Holland, it usually starts with 250.000 $ up to couple of millions and ends with permanent blocking for the really naughty ones.