The linking is just to help us find your key when troubleshooting license issues, etc.
If you choose the non-Steam key, it's a single machine license that can be installed using the installer from our website.
The Steam license can be used on multiple machines, as long as you're the primary user of the machine and can install Steam on it, as DisplayFusion needs to be installed through Steam for that license type.
Hope that helps clear it up!
