By default, each combination of OS_user+machine will require an additional unattended license. However, it is possible to optimize license usage for a specific use case. 

1) Single OS user that logs into multiple machines. 

A simple configuration you can add to the client’s appSettings.config file and it will always send a specific machine name to the console. As long as connected with the same OS user, this will use the same license.

Add the following config key with any textual value (for example : “CustomerABC”):

Note:

• Make sure to set the config before registering the robot
• You can have only one robot connected at a single time – we do not support multiple robot connections using the same OS user and the same machine name. 
• It should be done for all robots using the VDI pool and can be seen in the Admin to enforce them all.

2) Multiple OS users login to a single machine

Each additional OS user login will require one more unattended license. It's planned to support this scenario so only one license will be required in future versions. It might be implemented in 20.10 but not guaranteed. 

Thanks to Eylon for sharing it