Those Windows users who were hoping to score a discounted upgrade copy of Windows 8 Pro without being eligible for the offer are apparently in for disappointment because Microsoft has recently closed its promotion-page loophole which offered the cheap $15 Windows 8 upgrade offer.

For the discounted offer, the Windows Upgrade Offer website apparently worked on an honor system, since the cheap Windows 8 upgrade - the full digital copy of which costs $40 - is available for those new Windows 7 customers who had bought their Windows 7 PCs during the period between June 2, 2012, and January 31, 2013.

However, Microsoft's working on the honor system led to a Windows 8 upgrade loophole because the company had no mechanism in place to check whether the users who were availing the upgrade were actually eligible for the offer. The company simply presumed that the upgraders were being truthful about their Windows 7-device purchases.

As such, the discounted upgrade offer could be availed by anybody who filled out the requisite form, even with incorrect information about the date of purchase of a Windows 7 PC.

The company has now not only closed the Windows 8 upgrade offer loophole, but has also made it essential for the upgraders to enter a Windows 7 product key, so that the system can check out the validity of the purchase before extending the upgrade offer.