Activate Your Window 8 without Any Activator / Cr@ck / Patch ?

First of all 
* Open up command prompt as
administrator (Windows button + X)
* Type each line one by one and press
enter once you type one !

slmgr /upk
slmgr /ipk NG4HW-VH26C-733KW-K6F98-J8CK4
slmgr /skms
lunar21.no-ip.org:80
slmgr.vbs -ato

Done !

Lets learn for what these commands are used for :-
a.slmgr /upk - deletes the current serial
key you entered
b. slmgr /ipk SERIAL KEY - add the specific
serial you typed
c. /skms lunar21... - Connect to that kms
server
d. slmgr.vbs -ato - Activates the serial key
you entered before.

tested on Windows 8 Professional Retail build 9200 system operator