Logs of which host are using RD License Manager

I have inherited the RDS environment across 3 Domains.
Have recently built a new license server for current 2016/2012 hosts and i wish to migrate our old 2008 R2 RD licenses.

How can i track which servers are accessing the old RD license server??
Are there log files i can look at as there are VM's all over the place.
Group Policy hasnt been used so mostly manual setups so can look at a security group to assist.