Windows 7 Anytime Upgrade is a feature that allows users to upgrade their Windows 7 installation to a higher edition, such as Professional or Ultimate, without having to perform a clean installation. This feature was designed to make it easy for users to upgrade their Windows 7 installation to a more advanced edition, without losing their files, settings, and applications.
If you already possess a legitimate, unused Anytime Upgrade key, the feature technically still works on machines that are fully updated. windows 7 professional anytime upgrade key