The whole activation procedure is described in Office for Mac 2011 Activation and Product key Information (via ). Upgrade to a newer version of Office so you can stay up to date with all the latest features, patches, and security updates. However, you could expose yourself to serious and potentially harmful security risks. All of your Office for Mac 2011 apps will continue to function.
Support for Office for Mac 2011 ended on October 10, 2017.