Sit down with your son, ask him what he expects from you...then tell him what you expect from him. Come to an agreement together.
I have 5 daughters. Three have birthday's in the next few weeks...they will be; 14, twins 16, 18, & 20. Our house rules are firm. All of our kids will still be in high school when they turn 18...so one house rule is, nothing changes until graduation. Our twins will be 18 in Oct. of their senior year...but they too will have to wait until they graduate. We asked our oldest daughter what she felt was fair and why she felt that way. We came to an agreement together. She knows the consequences and doesn't like them. The only thing that changed in our house was her weekend curfew. She is able to stay out an hour later. We don't promote parties, we know she goes to them. If she EVER drinks and drives, she will lose her car...end of story. She loves having a car, so for her, that's enough. Until she can afford to move out and pay for her schooling and all living expenses herself, be smart and safe, then they can live with and off of us until they can afford to be on their own. Our oldest did the typical things to prepare us with our younger 4...she tried the "I'm an adult" thing with us...but we told her we would miss her living with us, but if she really felt that way, then we would support her. She can't afford that. That was a short lived phase, now she's willing to do a few chores and follow our rules without any complaint. She respects the fact that we respect her, most of her friend's are away at school, so her comings and goings are pretty much the same people. She isn't allowed to be gone overnight without telling us where and with whom.
As long as she follows the rules, which are really rather simple, life is easy. Our kids follow the rules and we rarely, if ever have to punish our kids. Our younger kids know the rules and believe what we say to be true. If my husband and I are going out, day or night, we tell them we will call them if we are going to be longer then what we think. It's about respect...we want them to know it goes both ways. We have left our kids alone overnight several times, from 2 to 7 nights. We never worry. We have friend's/family that will drop by and neighbors we trust...if anything looks 'funny', call the cops. We've told our kids, you pay the consequences of your choices. My kid's aren't little, they know right from wrong...they need to be held accountable. So far, my kids like living at home, they respect that we provide for them until they can provide for themselves. 18 is just an age, it's not a right of passage. Full adulthood comes when one can provide for their needs 100%.
The past 20 years have gone by so fast. I like having all my daughters home....they will all be gone too soon...I think they realize that their time together is limited also. I'm only 38, we had them young. I have come to the fact that they are growing up...I just never want to look back and say "I should have done it this way"....and so far, I think our ways are working...doesn't mean they would for other kids, but for us, we found a system that works...that's the trick, each family has to find the system that works within their homes.