Among the many changes in Microsoft Office 2011 in its product launch is "activation" that must be done over the Internet or by phone, for the first time in Office on the Mac, as revealed in a recent blog post Office for Mac Help. The site, which is an unofficial resource for Office Mac users, cites the Office 2011 End User License (EULA) as its source. Activation ties the use of the software to a specific device and reveals other information (such as IP address and hardware configuration), but can be reassigned to another device infinitely many times, with the only limitation being only once every 90 days.
The Home & Student Edition version of Microsoft Office 2011 (Family Pack) still has three licenses, but in the 2008 edition, each license that was useful for a desktop computer and a laptop, that is, up to six Macs in one home can run the software. The 2011 license limits each activation to one device, cutting the number of allowed machines in half.
Information sent to Microsoft during the activation process includes the version, license version, language, and product key of the software, as well as the IP address and hardware profile of the device. The post did not specify in detail what is included in the "hardware configuration".
The licenses can be reassigned to different devices, but it is limited to being able to do it only once every 90 days. If a device is "retired" (that is, it will not be used again due to sale or failure), users will need to contact Microsoft to reassign the licenses they used.
Source: Macnn.com