Out with the old, and in with the new. Microsoft yesterday stopped providing Windows 7 Professional and Windows 8.1 licenses to original equipment manufacturers (OEMs), including its PC partners and systems builders. This means that, as of today, the only way you can buy a computer running Windows 7 or Windows 8.1 is if you can still find one in stock.
Two years ago, Microsoft stopped selling Windows 7 Home Basic, Windows 7 Home Premium, and Windows 7 Ultimate licenses to OEMs. Now Windows 7 Professional and Windows 8.1 are also out of the picture, leaving Windows 10 as the only remaining option, assuming you want a PC with a Microsoft operating system.
This is Microsoft’s way of slowly phasing out old operating systems. The Windows Lifecycle chart for sales doesn’t have an end date for Windows 10, since that operating system doesn’t have a successor.
Read more here: venturebeat.com/2016/11/01/microsoft-stops-selling-windows-7-and-windows-8-1-to-computer-makers/