So much lazy parenting on this thread..
Smoking weed is not OK/something that all teens should just be let to experience with.
By buying weed you are giving your money to some seriously dodgy types and supporting criminal networks. Something that people often gloss over.
The stuff they are buying is likely to be mixed with all kind of rubbish.
Weed might be harmless and non addictive for many people, but for others it will be the start of addiction or will worsen existing mental health issues.
Plus what a waste of your money.
Frankly I despair when I read so many ''it's fine, just don't let them do in the house''...
OP just make it clear that this is not acceptable.
You are their parent, not their ''cool friend'''.
I had adult acquaintances who literally could not function without their daily weed break. It can turn into addiction and lead to other, more dangerous drugs.
She has done her teen experiment phase, now she needs to understand the implications and face the consequences.
Don't let anyone making you feel bad for acting as a responsible parent should.