The first Windows 8 sales promotion announced last year is now the final one to end: Today is the last day that purchasers of new Windows 7-based PCs can register to receive a huge discount on the Windows 8 Pro Upgrade. The cost? Just $14.99 in the US.

Dubbed the Windows Upgrade Offer, this special promotion applies to any Windows 7-based PC purchased between June 2, 2012 and January 31, 2013. As I wrote in Windows 8: Windows Upgrade Offer last year, the promotion is an especially good deal, even better than the temporary upgrade pricing of $39.99 that Microsoft offered between October and January. Of course, to qualify, you do need to have purchased a new PC in the specified time period.

The Windows Upgrade Offer is available in 140 countries and in 37 languages and consists of a promotion code you can redeem for a product key and online software download. If you do qualify, you have to pay for the upgrade, get the promotion code, and then download the software today. But you can install it at any time in the future, as you can create a bootable Setup disc (or bootable USB disk) during the process. (You can also purchase a Setup DVD as part of the process for an additional $14.99.)

If you were to purchase the Windows 8 Pro Upgrade otherwise, it costs $199.99. The lower-end Windows 8 (Core) Upgrade is $129.99.

You can register for the Windows Upgrade Offer on the Windows Upgrade Offer web site. Microsoft will ask you for some basic information about yourself and the PC purchase, and it may ask you for your Windows 7 product key as well, a change that was added after it was discovered that the original version of this offer didn’t require this, leading to piracy. For more information, refer to the Windows Upgrade Offer FAQ.

But act quickly: You must redeem your Windows Upgrade Offer promotion codes by the end of today, February 28, 2013.