If you want to know how many licenses that you have available and that your organisation have used so far, simply go to the SEP Management Console (MC).
Go to license tab. Here you get an overview of your license quota and available licenses.
If you want to have this information in report form, simply click Usage by Domain. A new window will open up and look something like this:
This window will give you an even more granular en more user friendly view. From this view you can now download the report as PDF or even as HTML.