Stress
It might be too simple but here's my idea:
Relapsing is mostly triggered by stress, right? Can't we just make addicts or former addicts wear match watches that track their heart rate? When their heart rate goes significantly up it will alarm the user of the heart rate to let him be aware of the situation. Not only that but the smartwatch also notifies his/her sponsor so that the sponsor could immediately contact him/her to see what's wrong and if there are signs of relapse.
Relapsing is mostly triggered by stress, right? Can't we just make addicts or former addicts wear match watches that track their heart rate? When their heart rate goes significantly up it will alarm the user of the heart rate to let him be aware of the situation. Not only that but the smartwatch also notifies his/her sponsor so that the sponsor could immediately contact him/her to see what's wrong and if there are signs of relapse.