Windows 7 Developer Activation - Kb780190 Site

The activation was not persistent and could be easily detected by Microsoft's Windows Genuine Advantage (WGA) validation checks. If users didn't keep their systems isolated from the internet, the activation would likely be flagged as invalid, and users would be required to reactivate or face limitations on their system's functionality.

Microsoft eventually patched the vulnerability and made efforts to clean up the exploit's aftermath. Users who had taken advantage of the exploit might have encountered difficulties with future updates, and their systems might have been flagged as non-genuine. Windows 7 Developer Activation - kb780190

You're referring to a rather infamous issue! The activation was not persistent and could be