You can just click I already have a product key
You'll then see the first screen in the Add features to Windows 8 wizard, which asks you whether you need to purchase a product key or you already have one. Just click the "I already have a product key button" to continue.
Credit: Images by Greg Shultz for TechRepublic
Greg Shultz is a freelance Technical Writer. Previously, he has worked as Documentation Specialist in the software industry, a Technical Support Specialist in educational industry, and a Technical Journalist in the computer publishing industry.