Sorry to butt in here, but activation and registration are two completely things. If Office has been activated with the correct key, then registration is completely optional. if you choose not to register, your Office install will work just fine even after 20 restarts. Heres what MS says about it.
"At the completion of the activation process for your software, you will have the option to register your software with Microsoft. Registration is not the same as activation. While activation is required in order for your software to work correctly, registration is optional and is completely separate from activation. When you register your software, Microsoft can send you customized information and offers regarding future products, as well as provide you with improved product support and product update information.
During the registration process, the software will ask you to enter information in a number of fields, including your name, e-mail address, and other information. Any information that you enter into these fields will be sent to Microsoft and stored in a subscription profile database.
Microsoft uses this subscription database to determine your preferences for product offers and services that may interest you. Microsoft does not share or sell your information with any third parties except companies acting as agents who perform services on Microsoft’s behalf. We will only provide those companies the personal information they need to deliver the service. They are required to maintain the confidentiality of your information and are prohibited from using that information for any other purpose."