How to Change the Product Key and Activate - Windows 8

In windows 8 you can change Product Key and Activate in two way. Normally Windows 8  doesn't providee the option directly to do this.
Method I - Move the cursor to the lower left hot corner, right click, and then click Run (alternately, press the Windows and R keys at the same time). In the Run dialog box that appears, type slui.exe 3 then click OK. The Change Product Key GUI will open.

 Enter the new product key in the text box. If the product key is valid, you'll see a message below the text box that reads, "Your product key works! Continue when you're ready." Press the Activate button.You Will Get Message "Thank you're all done".

Method II - Using Command Prompt Firstly, you need to go to the Windows 8 Charms Side Bar Select Search, type cmd and right click on CMD and select run as Administrator. Make sure you choose run as “Administrator” from the bottom options.Once the command prompt is launched with local admin privilege, run the following command to enter your activation key.
 slmgr.vbs -ipk YOUR ACTIVATION KEY HERE

 
 You will get a confirmation for the product key that you have entered. Then, run the following script to activate the product key slmgr.vbs -ato Finally, you will get a confirmation on product activated successfully .