Tips & Tricks: Change a Win7 or Win2008 R2 Product Key
To change or re-enter product key that already installed in the system, follow these steps:
Click on Start button.
Click on Computer to open Computer folder and then click on System Properties on the taskbar.
Tip: Alternative way to access System Properties page is by right clicking on Computer and then select Properties, or via Control Panel -> System and Security -> System.
In the “Windows activation” section, click on the Change product key link. If User Account Control (UAC) prompts for administrator password or confirmation, type your password, or click on the Continue.
In the “Product Key” text box, type in the new product key, and click on the Next button. If User Account Control (UAC) prompts for administrator password or confirmation, type your password, or click on the Continue.
Windows will attempt to activate online with the new product key, or display Windows Activation Wizard which user can follow to complete the activation process.