Oh, this is so easy to answer. A Valve-Anti-Cheat ban is only permanent as long as you are not prepared to pay them some money.
What's that you say, "But surely, if a ban is placed on a user for using cheats - and they have a 'zero tolerance' for such actions - then they can never be allowed to play again!"
OK, say that, but you are wrong...
I quote from the 'standard' answer to any enquiry about being banned,
"If you choose to purchase a new copy of the VAC banned game(s), please create a new Steam account to register the games on..."But wait, don't Valve also say that they will basically determine whether or not you are a "cheat" and ban you without telling you how, why or when? Yes, that's it.
So just to be clear...
- You go and buy a Steam game and register an account
- You use it for a while
- Valve determines that you are a cheat (you may or may not be, but that is irrelevant to them)
- You are banned from playing the game you paid for on secure servers
- You have no right of appeal
- If you want to play again, just go an buy another copy, create a new account and... off you go!