As far as I know vSphere with Operations Management (vSOM) Server Virtualization with VMware vSphere any edition doesn't come with NSX License and NSX is a separately licensed product.
Therefore you must buy separate NSX licenses
NSX supports any vSphere edition on vSphere 6.x and need Enterprise Plus on vSphere 5.x
Licensing vSphere 5.5.x/6.0.x and NSX for vSphere 6.x (2135310) | VMware KB
If you are using VMware vSphere 5.5 Update 2 and earlier, VMware NSX requires vSphere Enterprise Plus license for vSphere Distributed Switch.
If you are using VMware vSphere 5.5 Update 3 or vSphere 6.0.x, VMware NSX for vSphere 6.x does not require a vSphere Enterprise Plus license and can run on any vSphere edition.
NSX product offerings comparison is here:
Product offerings for VMware NSX for vSphere 6.2.x and 6.3.x (2145269) | VMware KB
Network Virtualization with VMware NSX Virtualized Network