How to Get Your Free Windows 10 Upgrade
If you have a Windows 7 Service Pack 1 machine or one with Windows 8.1 Update, and it passes the “genuine” test, you qualify for a free upgrade to Windows 10. To confirm whether you’re running the genuine stuff, go to Control Panel > System and Security > System. At the bottom you should notice that “Windows is activated.”
Win7 Starter, Home Basic, Home Premium, 8.1, and 8.1 with Bing get Windows 10 Home; Win7 Pro, Ultimate, Win 8/8.1 Pro, 8/8.1 Pro with Media Center get Windows 10 Pro. Note that Windows Media Center, if detected, is deleted from your copy of Windows.
As long as your current copy of Windows is “genuine,” the new copy of Windows 10 will be “genuine” ― and free. The caveat: You have until June 29, 2016, to make good on the upgrade.