I'll bet that ....
the first thing that this government comes up with is an annual license with ensuing ridiculous fee, followed by a license plate larger than the damn drone.
The US Federal Aviation Administration (FAA) has named the 25 people who will draft the blueprints for a nationwide database of drone owners. As promised by the FAA and US Department of Transportation (DOT), the task force consists of individuals from companies and organizations that make and sell drones, as well as pilots, …
A license plate as sole ID is unlikely simply because many drones don't have the panel space needed to display an N number with even 25mm (1") high letters and on top of that it would be unreadable from any useful distance. That said, having the reg. written on the side of every drone is still useful as passive, on-ground ID if you're looking for a lost drone or if a cop thinks you've been a naughty boy.
I'd guess the more likely solution would be some form of low powered transponder or simply a device that broadcasts the reg. every 5 secs or so. Either should be cheap enough to mass produce because it only needs a range of at most 2-3 km (1-2 miles). Using one of the longer range IOT radio link modules would hold costs, weight and weight power use down. As a sweetener, it could double as a finder for downed or crashed drones.
So, in the Land of the Free*, the drone you shoot down will be registered, but the firearm you shot it with won't be....
*Note: not a dig, just a bemused comment from a country where only criminals can buy guns. I fully support your right to arm bears and all other mammals with suitable upper-limb dexterity.