FlexNet Publisher license management software must be installed to manage ArcGIS Desktop Concurrent Use, ArcGIS Engine Concurrent Use, ArcInfo Workstation, Esri CityEngine, and ArcGIS Pro concurrent use software. Details upon the version of FLEXnet published used in each version of ArcGIS License Manager can be found in this Knowledge Base article. In an enterprise environment, ArcGIS License Manager can also host and distribute enterprise single use licenses or ArcGIS Pro and Premium App named user licenses via an on-premises Portal for ArcGIS.