There are two (at least) fairly easy ways to determine the number of concurrent sessions (some people say licenses but that's misleading) for environment. It depends on whether you have access to these two locations but it sounds like that shouldn't be a problem for you.
In Blue Prism > System tab > System group > License: This will have a list of Installed Licenses. Add up the number of Sessions across the licenses. If there is only one license installed, then the number under the field 'Sessions' is the number of concurrent sessions you can run in that environment, as per (1) your agreement with Blue Prism as well as per (2) the technical limitation of the license file itself. So, if it says 10, then you can never go above 10 sessions running in Control Room in that environment at one time. Blue Prism (the software) will reject/ignore any attempts to run the 11th session concurrently. You can test this by dragging a process (must be background mode) onto a resource to create a pending session and then keep dragging the process onto that resource until you have (for example) 10 sessions pending. When you try to create an 11th pending session, it will not work and should give you an error indicating your license does not support it or whatever.
In Blue Prism > Analytics tab: You can add a Tile from the Tile Library onto a Dashboard that will show your license limitation as well as your current license consumption. Right click on 'My Dashboards' and create a Personal Dashboard or Global Dashboard. Notice the Hamburger button at the top right that you have to click on in order to switch to/from edit mode. While in edit mode, go to the Tile Library tab (in Analytics tab) and drag/drop the Tile 'License Information' onto the dashboard you created. Then use the Hamburger button at the top right to save it. You'll see that it shows you your 'Limit' which is the max number of concurrent sessions you can run in the environment, and it will also show you how many sessions you are consuming currently under 'Used'. This only shows right now, not the highest you've consumed recently.
Dave Morris, 3Ci at Southern Company