Your PC ID / Device ID is a semi-unique identifier for a given installation of TracerPlus Connect on your PC or TracerPlus on your mobile device. These IDs are used in the registration process to assign your Device / PC to a license.
To locate your PC ID within TracerPlus Connect, you can go to Tools -> Registration, and then within the "Registration" tab will be a field containing your PC ID, which should take this form: PC-100-000-0000.
To locate your Device ID within TracerPlus on your Android or iOS mobile device you can go into the menu of TracerPlus, then the "About" menu item. From here you can see your Device ID.
To locate your Device ID within TracerPlus on your Windows Mobile device you can go to Help -> About and under the "Project Rev:" field you will see your Device ID.
More information about registering your TracerPlus software can be found on the page below: