On early Windows versions (95 or 98), where there was no internet, all you needed to activate Windows was a valid code. At that time, with any activation code that satisfied the decryption equation inside Windows, even a pirate code, was able to activate. With the same windows copy and code it is possible to install on more than one computer.


With Windows XP, to avoid pirateís codes, even with an activation code that satisfied the decryption equation inside Windows, MS began to verify, via internet or via telephone, if the code was a valid code furnished by MS. Once activated, at boot, Windows make a check to see if there has been any hardware modification since activation. Installing a new or different expansion card will lead to a new activation.
With the same Windows copy and code it is possible to install on more than one computer.

With Win Vista and Win 7, MS after verifying via internet or via telephone, if the code is a valid code, it began to record when the activation was done. To avoid unnecessary activation by installation or changing of add on cards, MS began to verify at boot if the LAN hardware MAC (manufacture code) hasnít change. As most LAN hardware is integrated nowadays to the motherboard, this check was to see if the motherboard hasnít changed. For instance, if you disable LAN on BIOS, Windows will claim for activation.
If you ever tried to reinstall Windows on a period less than a year or so from last activation, it wonít activate automatically, and you have to do by telephone. With the same Windows copy and code it is possible to install on more than one computer, using the telephone to activate.

I never did a Win 8 installation, but for what I read, I suppose MS is now recording the LAN MAC when you first activate, so it will activate automatically regardless when it was last activation, as long as it has the same LAN MAC, or in other words, same motherboard. Donít know what is the procedure to activate if you change your motherboard (and the LAN code associated). Also donít know if, with the same Windows copy and code, it is possible to install on more than one computer, using the telephone to activate.

Now letís understand how Win 10 is activated. There are two scenarios:

- You have original win 7 or Win 8. You CANíT use your win 7 or Win 8 code to do a fresh install. You will have first to do an upgrade on your win 7 or Win 8 (run setup from inside Windows, I suppose), MS will then verify if your win 7 or Win 8 is original, record your LAN MAC and activate. After this upgrade activation you can do a clean install using the same motherboard (LAN MAC). You just skip inserting the code during installation. To activate, MS wonít verify the Win 10 code, but if the LAN MAC has been used before during an update. Of course, if you have used same Windows 7 or 8 code in more than one computer, only the first one to activate will activate automatically.

- You by a buy a Win 10 code. In this case you have to insert the Win 10 code you bought during installation. For what I read, I suppose MS will record the LAN MAC when you first activate, so it will activate automatically regardless when it was last activation, as long as it has the same LAN MAC, or in other words, same motherboard. Donít know what is the procedure to activate if you change your motherboard (and the LAN code associated). Also donít know if, with the same Windows copy and code, it is possible to install on more than one computer, using the telephone to activate.

Iím not planning to do the update right away, for obvious reasons. Many bugs to correct and there will be many, many problems and fixes on the next months ahead. The ideal is to wait the first service pack before installing a new OS.