If you bought Windows 8.1 or Windows 8, you can download and install Windows from this page using just your product key. You’ll have the option to install Windows now, later, or using media with an ISO file.
Before you begin:
Make sure you’re on the PC you want to upgrade. If you’re updating to Windows 8.1, this PC must be running Windows 7 or Windows 8.1 Preview. If you already have the latest version of Windows 8 installed on your PC, you can update to Windows 8.1 in the Windows Store for free…
It's my life, you're just along for the ride! 