One of the key antipiracy measures in Windows 7 have been cracked, bypassed to be correct. I’m not that familiar with procedure itself but it is well explained in this post.

Anyhow, if you use Windows 7 you are aware that you had to activate you copy of Windows within 30 days. If not, some of the functionality of the OS become unusable. this process now has been bypassed…

On the other hand it doesn’t mean that this hack makes your copy of Windows 7 legitimate but it allows you to keep usin your product indefinitely.

Microsoft confirmed the issue, and stated that they are working to fix the problem.

Source…