How do I find the product key for Windows 8.1

Original title: Product Key

I downloaded Windows 8.1 (free) from the Microsoft web site. My understanding was that in doing so, a new product key would be generated. I do not know where/how to find the new product key. Can someone help me out with this? Was I mistaken and do I use the product key I have for Windows 8?

MY P.C. IS AN ACER DESKTOP WAS RUNNING WINDOWS 8  WHEN NEW  (NOW)

windows 8.1 was put on by a member of staff at p.c. world where I took it to get

repaired?(It was under contract policy with them 

I had windows 8 on when it went in TO THE SHOP ?

NOW I have windows 8.1 on it  the problem is I have a tower desktop i paid for from 

p.c. world already set up and running windows 8  by them?

the point is I got no start up disk with my p.c. only a U.S.B. STICK with startup information.

so if I wish to get somthing to update for my windows 8.1 it says put your product key

number in i cannot because I have NO PRODUCT KEY NUMBER?

What I am asking you is can your help me find my key number it must be on my p.c.

some where can you point me in the right place to find it

That feature you mention REQUIRES you purchase a product key for the product you wish to install. Right now about the only thing available is an upgrade to Windows 8.0/8.1 or Windows Media Center. It is not meant for anything free at this point. Hope this helps and if you need any further assistance post and we will be glad to help you.

The above opinion is mine and mine alone and doesn't necessarily reflect that of Microsoft, it's employees, or any other member of this forum.

"When we try to pick out anything by itself, we find it hitched to everything else in the Universe." - John Muir

If this answered your post Please mark it as answered

Worse is that the Control Panel now has an icon to get Features for Windows 8.1 for which its product key is required and it says that it is not the product key that came, when you installed Windows or when you purchased your computer!

Keyfinder worked! I have successfully reverted  to Win.8 and am using it now. Got to have that keycode.

Yes I upgraded from Microsoft per the "Free upgrade to win.8.1" prompt that kept popping up. Just now I DID download and use 'keyfinder' and it found 'match to CD Key data.

CD Key:  which is different from the product ID found at the bottom of the "system" page. Will this work?Some of the forums are doubtful that it will.

"keyfinder" utility worked and I am now back to Win. 8

 Also our thread>http://answers.microsoft.com/en-us/windows/forum/windows8_1-system/any-idea-how-to-revert-to-win-8-from-win-81-wout/4961fda7-c6ca-4af1-bc5a-302590f3eedb