I dont know if there's something specific for RDP, btw you could
- enable an Audit Policy for Logons
on the workstation (you can do it via GPO if you're on a Active
Directory domain or you can do it on a single workstation editing its
Local Security Policy)
- check Events in Security with Event Code = 528 (User logged in) and
Logon Type = 10 (Remote Interactive, so RDP like connections)
you can query Events i.e. using LogParser (GUI here) and maybe load them in a DB for future analysis