The Product Key consists of 25 digits, divided into 5 groups of 5 digits and the layout looks like this: Read Section: Beware of Product Keys sold you did buy 7 and you lost your product key or it came preinstalled: Make sure that you buy the complete sealed package (DVD, license) You do not buy a Product Key by itself, as they are normally stolen/pirated, Volume Licenses which are not for private use, or MSDN keys which are not to be sold by the original subscription holder.