I've been on Mac & iPhone for a long time & this summer purchased a 1Pass 7 license. (I've been on 1Pass for a long time too.) I just got a Windows machine and was trying to add my license; it appears that the licenses are OS-based instead of person-based? When I click "add a license" in my Windows 1Pass app, it doesn't see the (Mac?) license file that I downloaded. Changing the file extension and name format to the one I've seen online as the Windows license format will cause the file to show up for 1Pass, but the Windows app doesn't know how to interpret the file contents.
1Password Version: 7.3.712
Extension Version: Not Provided
OS Version: Windows 10
Sync Type: Dropbox