If I have a license with only one client admitted, would be the “localhost” machine count as client if I open a project viewer, or a client is counted only if the project is opened from a different device?
With “localhost” machine refered to the machine where the gatweay is installed.
I believe you can open one client on the localhost (which counts as a dev client) next to the actual client. Otherwise it becomes hard to develop Ignition.
See also this forum post:
But if you already have such a license, you can try it out.