You don’t, I haven’t had a decent nights sleep in years. 
Seriously, he went through a phase in his teens of leave me alone, you don’t need to know everything. Bloody hard.
One evening when yet again he had failed to update me, he roared WHY Mum, Why, I roared back, it will give the police a good place to start.
Cue dumbstruck silence, he checks in 9/10 these days. 
When he was being particularly tight with his information in his teens, DH and I made a point several times of going out and leaving the house in utter darkness and not answering the phone the first time, when the inevitable where are you call came, we would reply loftily oh just out, he didn’t like it very much and things improved from there.
Last weekend he went out, we live in a small town, nowhere open after midnight, I waited until 2,30 and texted WTAF, he rang and said sorry we are at X’s, I replied stay there as long as you like, come home when you like, now I know that you are not in a ditch, party on.
The worry increases when they have their own car.
It is truly a fine line, between giving them roots and wings.