Set ArcGIS license - e.g. in CITRIX

In Citrix, multiple copies of a process (e.g. ArcMap application) are run on a Citrix server.

Therefore Concurrent Use is supported as the only licensing method in Citrix environments.

License switching for a single user with ArcGIS Administrator is then not possible. 

Instead, the environment variable ESRI_SOFTWARE_CLASS is used:

ESRI_SOFTWARE_CLASS=Viewer
or:
ESRI_SOFTWARE_CLASS=Editor
or:
ESRI_SOFTWARE_CLASS=Professional

The license selection/switching with this variable works of course also in "normal" Windows environments.