In 2015, the Federal Aviation Administration (FAA) attempted to address the proliferation of drones and some of the hazards associated with their operation with a rule requiring that all “small unmanned aircraft” register with the FAA.
The online registration process created by the 2015 rule, which the FAA says is intended to allow owners of small unmanned aircraft to comply with a statutory registration requirement, was designed to be less onerous than existing regulatory requirements in order to accommodate owners of these aircraft.
Registration requires owners to file online and pay a $5 fee per small unmanned aircraft, or a $5 fee to register a “fleet” of such aircraft, with mandatory renewal every three years …
https://fas.org/sgp/crs/misc/faa-drone.pdf
Congressional Research Service | 6 June, 2017