How to Register Your Drone in the USA
If your quadcopter weighs more then 250 grams you will need to register. The fee is only 5 dollars per person, so you can fly an unlimited amount of UAV once registered.
The Small Unmanned Aircraft System (sUAS) Registration Service registermyuas.faa.gov
Via Adafruit Industries | See their learing guide: learn.adafruit.com/how-to