In PC-Based licensing, a serial number is applied to the PC and any number of terminals can upload or download data to that PC. Each PC that will be used for communication requires a PC license. For the Omni Server, the PC also requires Terminal Pack licenses matching the number of terminals that will be connecting.
In device-based licensing, each terminal receives a serial number. The device can then communicate with any PC running the software, and no serial number is needed on the PC.
Note that in either case, the Program Designer still requires a Developer serial number to save a data collection program that will not have the Demo limitation.