You get demo licencing in a similar way to CUCM - enough to set up a lab with.
For example, you get two ports so two calls can be made/received at the same time and 10 mailboxes.
I hope this helps.
Here is what Cisco say:
Demonstration license files are not registered to a MAC address. These license files do not have an expiration date and enable only a limited range of features (for example, a maximum of two voice messaging ports and ten users with voice mailboxes). A demonstration license file is included with every Connection server. If this license file is installed, it must be the only license file that is installed on the Connection server.
I can't seem to find Cisco Unity connection for download on the Cisco Site. I do have a CCO account.