only one Enterprise Client license will be required for each (physical) ESX/ESXi server regardless of the OS type and number of virtual machines running on that ESX/ESXi server.
NetBackup for VMware requires an Enterprise Client license for each ESX/ESXi Server. Enterprise Client is purely based on the Physical Processors installed on Virtualization Host.
and other licences requirement will be depends on your VM infrastructure
please refer below link
http://www.symantec.com/business/support/index?page=content&id=HOWTO44409
