Carrots,
If I'm not mistaken, you mentioned that she would not have a car while she is away at college and that she would be using it while she is living at home. Is that correct?
The congrats are for successfully setting your boundaries which allowed your daughter to own her choices. Creating a successful change and recovery for your daughter.
Carrots, I am not implying that you are responsible for her addiction, nor would you be for any future relapses.