By using Windows Key Viewer, the current computer product key can be easily determined. In some cases it is very important to know the product key, e.g. when reinstalling the computer.
Generally, the product key can be found on the Windows installation kit or on a label on the computer. This label often gets damaged and becomes illegible, and when using multiple computers, installation packages can get mixed up. That is when Windows Key Viewer becomes useful, as the product key can be easily displayed with it.