we are getting ready to deploy arcgis enterprise 10.9.1 and I have a question in regards to license manager. Currently we have a license manager running but we are building a brand new environment for arcgis enterprise 10.9.1. My question is should we run a brand new instance for license manager or can we use our existing license manager to license our new environment? Thanks
The license manager may need to upgraded to a version that works with Enterprise 10.9.1, but there is no need to standup a second machine in support of Enterprise.
Only named user licensing is supported through Enterprise, and if a license manager server is in place already I would guess you are using concurrent licensing instead.
Whether the license manager is used for Concurrent Use license or Named User license with ArcGIS Enterprise, it's a good idea to upgrade the license manager to the latest version. Later version of ArcGIS Pro may require a later version of the license manager. The latest license manager will always work with earlier version of Pro.