DL appliance licensing is a bit different from software Cores. DL appliances are usually licensed in 2 modes:
1. By repository capacity
In the capacity mode, DL appliance can protect unlimited amount of agents, but have a license-limited amount of data, that can be stored in its repository (in compressed form).
2. By number of agents
While this mode is quite self-explanatory, there are subtle differences with software Core servers. Software Core can protect X amount of physical agents, and/or VMs, counted by number of CPU sockets in hypervisor. If VM is protected by agent and not agentless, it'll also consume a license, unless it's "linked" to hypervisor entry.
Hypervisor on DL appliances is only consuming 1 license, regardless of amount of CPU sockets.
For example: DL with 8 physical machines and vCenter (12 CPU sockets across multiple ESXi hosts), protecting 30 VMs, will only consume 9 licenses.