Sometimes you're not sure what you're licensed for, or how close you're to fully using all that you're licensed for... you can normally find this through NetVault, by doing the following
1. Launch NetVault GUI Console
2. Click on the menu called "Administration"
3. Click on Domain Management & a new window will appear
4. Right click on the server name on the left, which should be your NetVault Backup Server
5. Click on "Properties"
6. Once this new window appears, click on the "Usage" tab... here you will find three columns, one for description, one for what you're currently licensed for and one for what you're currently using against that license.
"Description" "Licensed" "Used"
Number of Clients 50 45
This shows you can still add 5 more machines, as NetVault Clients, to backup if needed. (see attachment for visual example)