Upgrade

Take a look at Windchill licensing FAQ

https://www.ptc.com/en/support/article/CS277468?source=search#lm25

Windchill is licensed on a per user basis. You can as many instances of Windchill running as needed as long as you do not have more users in the LDAP than your company is authorized to have. I have 5 running Windchill systems, 2 production and 3 running testing for upgrades.

You would need to register the new host in the new licensing tool, and declare it as staging / test. Then you could apply all the same licensing to that server, You can have as many dev/test/staging servers as you need to.

A couple of notes before you do your upgrade test. You Admin user CANNOT be a member of any licenses in the pre-upgraded system, otherwise once upgrademanager completes, that user will not be able to see the licensing page to upload a new license.  Do you plan to do a rehost upgrade, or an upgrade in place of the backed up / restored server?

The guid for the host of your WC 12 installed machine will change after you run upgrademanager.