I bought mine at Axiogame as well. My card advised me that it was charged, but Axiogame's site still showed my transaction was still in process. I had to email them about it, and 6 hours later, Axiogames sent me the valid key.
You don't have to. I put the new boot.dat to the root of my directory, and it worked well without reauthenticating it. My license was recognized immediately.