I accidentally came across information that requires drone operators with any drone between 0.55 and 55 pounds to register with the FAA (USA fliers), under either part 107 or part 336. Refer to this article Just in Time for the Holidays, Drone Registration is Back
Registration is $5 for part 336...
Now that we are all registering our drones with the FAA I'm now offering a sheet of vinyl decals with your registration number. Decals are sold in sets of 8, you will get (4) 3" wide, (2) 4" wide and (2) 5" wide decals. They are available in Mettalic Gold, Metallic Silver, Red, Black, White and...