Licensing is per machine... You'll need to contact Cisco sales to get where the price breaks are.
3 levels of the product:
Essentials, which is just the endpoint security product
Advantage, which includes Orbital, a tool based on OSQuery to get more data about what's happening on your endpoints
Premier, which includes a team at Cisco that is running threat hunts across your endpoints via Orbital, and will alert you when they find things that need to be dealt with.
