Visit the official Autodesk Product Registration and Activation page from a device with internet access.
The next day, John decided to investigate further. He tracked down The Revit Wizard to an obscure corner of the internet and sent them a message. To his surprise, they responded, revealing that they were, in fact, a former Autodesk engineer who had grown tired of the corporate world and now dedicated their time to helping those in need. Activation Product Report: Revit 2009 Serial Number Visit