Hi, I'd like to help you with your question.
It is good that the communication between you and your son is open about this problem. However, sometimes children use this as a way of explaining away their behavior to gain your sympathy and permission to continue with bad behavior. I am not saying this is what your son has done, but it is a possibility.
It is probably very difficult for your son to move around a lot. New schools and new homes are hard to adjust to. But acting out is not the only option, just the option he has chosen. Since this is not the first time he has broken your trust, your concern is justifiable.
Your idea of having your son in counseling is excellent. He will have the opportunity to express his feelings about moving around and vent his frustrations. The therapist can help him find healthier ways to cope with his feelings and to express himself.
It is also very important that you and your husband find ways to enforce the family rules and stick to them. At age 15, your child should already have regular chores, have an allowance he manages, and have rules at home he follows. Punishing kids, especially teens, for their wrong behavior is difficult and the kids do not make it easy. But psychologically, children benefit from parents who consistently enforce the rules in the home. The boundaries help children feel loved and cared for, no matter how much they protest about it.
It is important that you chose punishments that you feel allow your teen to earn back your trust. For example, if you feel you need to let him do activities that you can monitor, then let him know you expect him to earn your trust back before you will allow him more freedom. Make him responsible for his own behavior, much like you or your husband would be if you did something dishonest at work or to a friend. He needs to learn to think like an adult so making him earn back his privileges is a good way to approach his behavior.
Besides counseling, here are some other resources that may help:
I hope this has helped you,