Introducing Windows 10 Editions
Windows 10 Home
Windows 10 Mobile
Windows 10 Pro
As we announced earlier this year, for the first time ever, we are offering the full versions of Windows 10 Home, Windows 10 Mobile and Windows 10 Pro as a free and easy upgrade for qualifying Windows 7, Windows 8.1 and Windows Phone 8.1 devices that upgrade in the first year after launch.** Once you upgrade, you have Windows 10 for free on that device.
http://blogs.windows.com/bloggingwin...medium=twitter
there is more listed not free though the ones 1 listed are the free ones