License info for CME is to some degrees an "honour system", but the maximum number of ephones and ephone-dns you can have is primarily limited by the hardware platform (2801 is approx 25 ephones & 80 (or so) ephone-dns) and the IOS version you are running. I remember reading somewhere that when you buy a Cisco phone, it comes with the license to allow you to use it on CME, up to the maximum permitted by the hardware (but don't quote me on that one). That being said, I've never heard of any one getting caught out on CME licensing.
CUE on the other hand does have a license file for the number of mailboxes and and another for the number of IVR ports. As far as I can remember this can only be checked by logging into the CUE device via the CLI and doing a show command (can't remember which), not sure if it is available via the GUI.