Windows 8 reinstalling with the same product key

Hello Guys , So I have founded this site in Microsoft : Upgrade Windows with only a product key - Windows Help (http://windows.microsoft.com/en-us/windows-8/upgrade-product-key-only) which i think it may help me to reinstall windows , So I have windows 8 and i used some programs to get my product Key then , i thought if i downloaded windows 8 again from the site and used the same product key...