[WPCentral Question]

I do not have the original version of windows 8.1 can i upgrade it to windows 10 for free?

[mjyumping]

Yes if you mean it is the pro version you have.

[xandros9]

I'm not sure I understand entirely.

Illegal copy? You can upgrade, it'll remain illegal.

not the original OS on the computer? You can upgrade.

[sourav ghosh969]

i had pirated 8.1 os but now i use preview version of 10 and when i gave the product key it was shown you are using genuine windows,

[Roland Schlangen]

i had pirated 8.1 os but now i use preview version of 10 and when i gave the product key it was shown you are using genuine windows,

That key is only valid for the preview build of win 10. It will expire on July 29th. So after this date you will not have a genuine copy.

There are several options to get a genuine Win10 RTM:
1. Upgrade to win10 from a genuine win7/sp1 or a genuine win8.1
2. Buy a new copy of win10 (available after July 29th)

If you did a clean install of win10 (build 10xxx) it will not be genuine from July 29th on. You still NEED win7/sp1 or win8.1 genuine.