Based on the above blog and this comment.
Cisco is offering its market-leading S-Series web security appliances in a virtual form factor: the Cisco Web Security Virtual Appliance (WSAV). You can instantly provision the WSAV where you need them to respond to sudden capacity spikes or to meet business objectives. It runs on VMware ESXi Hypervisor and
Cisco UCS® servers and you can mix and match deployments of both physical WSA appliances as well as virtual appliances.
Best of all, the WSAV license is included in all Cisco web security appliance software bundles (Cisco Web Security Essentials, Cisco Web Security Antimalware, and Cisco Web Security Premium). This license can be used for as many virtual machines as needed, making it easier to respond to capacity and budgetary surprises as they happen.
is it necessary to purchase the hardware appliance at all? or should a reseller be able to just sell me a part number such as WSA-WSP-1Y-S1 for the annual user based licenses? and i'll be eligible to deploy WSAv however i want, with any number of virtual appliances?