Symantec Endpoint Protection 11.0 uses the Symantec-standard “per-user” perpetual license model. The formal Symantec definition of the “per-user” meter allows several interpretations of the metering method, including user or device. As it applies to Symantec Endpoint Protection 11.0, one license must be purchased for each standard (i.e., non-virtualized) endpoint device running the software, regardless of endpoint type (e.g., server, laptop, workstation, etc.). For virtualized environments, (e.g., VMware or Terminal Services), each separately installed and concurrently running instance of the software must be licensed
You require 16 licenses: one for the server itself and one for each user, either on the remote host or the Terminal Server, but not both. If each of the 20 laptops/computers used to access the Terminal Server are licensed, then only the one license for the Terminal Server itself need be additionally purchased. If the remote clients are not licensed (such as thin clients that cannot run the Client), then the full 16 licenses should be purchased for the Terminal Server. The remote hosts and the Terminal Services users do not both need to be licensed.