How to check and know how many servers connected to single citrix license server in Xenapp 6.5 and 7.X environments?

up to xenapp 6.5 every "worker" connects to the licenseserver ... since 7.x the DDC(s) only connect the licenseserver.
within licenseserver-dashboard you can see the servers connected to the server and licenses used.

Any Script or Commandline tools available to get Server / Worker / VDI Name?

In my three 6.5 farms created a Citrix police points to one Citrix license server(ABC)..and also in every server regkey, I can see same license server loading.. actually from license server console I can see licenses expired in 2017 but still entire three 6.5 farms running without any issues.. Am afraid to upgrade OS to 2012 r2 on license server now..

"licenses expired in 2017" .. Citrix License don't expire. Only the SA expires. So you are unable to install new versions (of Xendesktop) or got Support.
The LicenseServer it selve don't use a license. You should be able to install new LS-Version at Win 2012++

Thank you, Drik.

Any Script or Commandline tools available to get to know which XenAppServer / Worker / VDI Name using license from LS ?

Thank you, Dirk.