Well it tells you on that unauthorize page what you need to do to fix it.
Go to
this page. You will need to use your customer number and customer password you were provided when you purchased your copy of vbulletin. Enter your username once you open that page in one of three fields and save.
If you never purchased a legal license you shouldn't need any hacks. Vbulletin hacks don't work without vbulletin. And piracy is bad.