How To Check Windows RDP Version

To know the version of Windows Remote Desktop  Protocol (RDP) in your Windows Computer :

Launch Windows Remote Desktop Connection from Start Menu (Accessories-->Connection-->Remote Desktop Connection)
Also you can launch from Run Command (press Windows+R , write :  mstsc , then press enter or click OK.
If using Windows 8, from Metro Interface write : remote , it will automatically searching and find Remote Desktop Connection.

After Remote Desktop Window appear,  right-click on the small icon (left-up side), then click About

Now you can see the version of RDP.

figure :  Remote Desktop Connection Version