The free upgrade to windows 10 still available. I did'nt know why windows do this, but in my search of this category i found these
one, a perfect PR
two, more not support to piracy software
three, minimali cost
four, estabilish platform
who get it:
not every Windows 7 or 8.1 user will get a free upgrade. enterprise editions of both Windows 7 and Windows 8.1 are excluded from the upgrade offer, though ‘Pro’ editions are included.

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic