We do offer an alternate licensing method called BYOD, in which you license the actual AMX control system. When an AMX system is BYOD licensed, any number of TPControl devices (licensed or unlicensed) can concurrently be connected to the AMX system.
If all that you are looking to accommodate is the case that they lose a device and need something immediately to get up and running, you can pre-configure the Settings and TP4 file for a TPControl 21-Day Trial license (you can generate those anytime using the TRY links on our Products pages, and the trial does not commence until you actually register a device to them), and provide the registration details to your customer. They register the device and perform a 'TPCloud update' to retrieve the Settings/TP4 and they have a backup device for the next 21 days while the situation with their other device/token is resolved.