I downloaded the installation media for Windows 10 Professional from Microsoft's website per the instructions in the product's description. During the Windows installation process, I selected "I do not have a product key". After Windows was finished installing, I went to "Activation Settings" from the Start menu. I selected "Change Product Key" and entered the key purchased from this site. Windows activated immediately. I did not have to call the toll free number. Thank you.

I bought a key, didnt work and sent an email to them. They responded within the hour and were happy to help.
Great customer service!

For those wondering if this is legit, it actually is. At first, my CD key had already been used, so I contacted customer support and received an e-mail with a new code within 3-5 minutes! The new code worked, by the way. You will not find it cheaper anywhere else, and the customer service is fantastic! I do not normally write reviews, but this website and its owners are well-deserving of it! 5 Stars from me!

immediate delivery, worked great

Awesome service, third key bought on gamers-outlet (2 W10 Home retail, now 1 W10 Pro retail), code delivered in 5 minutes, used to upgrade from W10 Home on a Rog G15 laptop to W10pro. Worked like a charm