You will need to open the Gemalto Admin Centre to check this information. If the webpage is opened from a user's machine you will be unlikely to have permissions to view session information, this can only be seen by viewing the Admin Centre on the machine the licence is connected to.
On the machine where the licence is located, open http://localhost:1947
On the left select Sentinel Keys. This will display the licence available and some details
Features will show the expiry dates, number of live logins for each module and the limits for the key (how many people can use this at one time)
Sessions will show you the names of the users connected to the Licence