Ciao 

I didn't remember that there were VMware Workstation for VM licenses.
Normally the Vmware Workstation license is tied to the installation of the VMware Workstation software.
1 license = 1 Installation of Vmware Workstation.
1 Installation of Vmware Workstation = n Virtual Machine (limit only to the HW where VMware Workstation is installed)
Do you have more details of the license they sold you?