Upgrading from Windows 7 to Windows 8.1 using the image I purchased and downloaded from Microsoft

About a year ago I purchased and downloaded Windows 8.1. Also, I burned that image to disc. So far, I've only used it to create a virtual machine. I'm wondering whether I can use that image to upgrade the host machine, which is running Windows 7. I've made one attempt to use that disc to upgrade Windows 7, but bailed out when I got to the install button without ever having been given a choice between a full install and an upgrade. Am I chickening out too soon, or is my fear that my system is about to be clobbered, justified? Can I use the 8.1 disc that I created to upgrade my Windows 7 system?