How to Activate window 8

Move your mouse to the top right corner and click Search.

Type cmd in the Search Box then click on Command Prompt (this appears on the left side, under Apps).

Type slui 3 (note there is a space between slui and 3) in the Command Prompt window and hit Enter.

Type the product key given to you when you downloaded Windows 8 from the software site. Click Activate.

Done 

source: online 

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