your drone will automatically fly or return to home when it disconnects from the remote controller while airborne afar, when the battery runs lows, or when you command it to do so using the return-to-home button. where is "home?"
home is based on your settings and home can be wherever you launched the drone from, home can be wherever the remote is currently located, or home can be a custom location which you can designate.
it is important that you experiment with these settings so you are intimately familiar with how they work. you don't want to get into an emergency situation and then have to figure it out; it may be too late. please read the manual on the exceptions to "return to home" and how to cancel return to home. then find a wide open field with little to no obstacles and then try it out for yourself. remember, you can always press the pause button if something happens that you don't like.