If you have ever received a licensing error on your Desktop Delivery Controller like the one below, you have most likely selected the wrong Product type during installation (Standard, Enterprise or Platinum). You can change the product version of the DDC by running the ProductEdition.exe command located in the C:\Program Files\Citrix\DDC directory.
ProductEdition.exe SetEdition Edition=STD [or ENT or PLT]
Sets edition to Standard, Enterprise or Platinum.
will display the current version.
Once this is run, reboot your DDCs and you should be good to go!
Another scenario where you might need to switch the product version of the DDCs is during an upgrade from the Free XenDesktop 4 Express Edition to a fuller featured paid for version.
If you have not had a chance to check out XenDesktop, Citrix is offering a FREE forever (NOT an Evaluation) version that will support up to 10 Users. Perfect to get your feet wet in the VDI space and the price is right.