Microsoft finally joined the free OS movement by offering the free upgrade for the new Windows 10 to come (and yes, they decided to skip Windows 9). Well, to be fair, with some catch.
Here is the offer detail from the Microsoft website:
Great news! We will offer a free upgrade to Windows 10 for qualified new or existing Windows 7, Windows 8.1 and Windows Phone 8.1 devices that upgrade in the first year!* And even better: once a qualified Windows device is upgraded to Windows 10, we will continue to keep it up to date for the supported lifetime of the device, keeping it more secure, and introducing new features and functionality over time – for no additional charge. Sign up with your email today, and we will send you more information about Windows 10 and the upgrade offer in the coming months.
The fine print listed some editions that are excluded from this free offer.
Some editions are excluded: Windows 7 Enterprise, Windows 8/8.1 Enterprise, and Windows RT/RT 8.1. Active Software Assurance customers in volume licensing have the benefit to upgrade to Windows 10 Enterprise outside of this offer.
Basically, you need to be retail version or OEM version to qualify for this free upgrade offer.
You can find out what edition you are using by typing the following command in cmd window.
> slmgr.vbs /dlv
You will see a window pop up like the following.