As soon as you assign a license to a workspace, it will be moved from your personal licenses to the Workspace.
All devices that use that license and are connected will stay connected. The connection with cloud is not optional in such cases anymore, as EAM uses its license
This behavior is intended.
When you want to remove a device from the Workspace, you can either choose another licence in EAM, after you logged in or switch to trial in About / License: change license
In fact, when you remove the device from the WS, EAm should popup the change license dialog automatically, but that doesn't happen yet.