That's not it. I understand only 2 machines can be logged in.
What happens, the machine I want to work on, for Photoshop CC 2017 or 2018 or LR CC I get the old style log on (if that machine is not logged in) telling me I need to log off. I let Adobe sign me off of all other machines, and it allows the log on.
All is good, no changes, no other log ons from other machines, then I open Photoshop 2019 CC, that brings up a totally different looking log on screen. Shows all the machine I have ever logged in with, and the machine I Just logged in, is showing Not logged in. Even though it is for all other Adobe apps. I have go through the entire process again from the different logon screen, and then Photoshop CC 2019 works.
Paul C