Windows 10 was introduced to the world as a free upgrade. This means that as long as you had an official copy of Windows 7, Windows 8 or Windows 8.1 installed on your machine, you could upgrade to Windows 10 free of charge. It was a very convenient gift for users and a sure way to rack up surefire market share for the newly released OS.
Some time after Windows 10 was launched, Microsoft announced that the 29th of July 2016 was the last day in which Windows 7/8/8.1 users could upgrade for free. Of course, no one expected things to be otherwise so when that date came, people pretty much forgot about the free upgrade feature which supposedly was shut down.
Ed Bott, a ZDNet representative, is the one credited with the discovery. Upon trying to undergo the free upgrade process on a machine using a valid copy of Windows 7, he was able to discover that there was nothing stopping him from completing its. The Microsoft page which hosts the option of downloading Windows 10 for free is still up and running and people can get their free Windows 10 copy even now.
There a couple of interpretations of this situation, but all of them are speculation since Microsoft has decided not to comment so far. No one can blame them since there isn’t a positive answer. The explanation for what happened could be as simple as Microsoft rewarding curious adventurers that visited the page after July 29, but that’s unconfirmed. Some are going for the funnier version of the story where Microsoft simply forgot to shu down the whole thing.