I had expected this capability to expire with the release of the Windows 10 Anniversary Update.

Note: Please understand that the loophole that allows this to work could (and should, I think) close at any time: All Microsoft has to do is to is turn it off from the cloud, it wouldn’t even require an update to Windows 10.

According to Windows Product Key Update Tool instructions, Windows Product Key Update Tool will make changes to your Windows installation to update your product key.

That group consists primarily of those who took advantage of the year-long free upgrade offer that ends on July 29, 2016.

This new feature doesn't change the fundamental way that Microsoft's activation servers work.

here is already a lot of product keys and serials utilities that allow you to change product key or CD key of Windows XP to another product key, in the case you’re bought another genuine and legit license, upgraded, lost the original serials, etc, or volume license key (VLK) if you or your company just switch to volume licensing arrangement.

Microsoft has also provided its own tool to change Windows Product Key, which supposedly to be most reliable, risk-free and won’t mess up your system.