SharmaDTS :
Dunlop0078 :
Yes you need an activation key. I believe It will still work without for about a month without it. Is this a legit copy of windows that you bought? If so it should have came with the activation key.
I entered Windows Key at the time of installation any other key you are talking about?
My Windows 8.1 came with two disc 32/64 and a Key it is genuine as far as I know
During the install, on the screen where you entered the license key, there was a checkbox for :"Activate online"
As long as that was checked, when you connect to the internet, it should activate.
You can check the activation status thusly:
Open File Explorer
Right click on 'This PC', select Properties
It will say down at the bottom of that Windows whether it is activated or not.