Hi Ron
in short, the answer to this is yes.
You can actually order/purchase UCSS without having ESW in place, however you will not be able to activate it. UCSS is effectively a PAK key that you need to register on Cisco's licensing portal. Part of the registration process is to provide your ESW contract number. If you don't have an active ESW contract on the product you have bought the UCSS for, the Cisco UCSS will reject the registration.
This is the voice of experience talking....
HTH. Barry