Can My Husband Still Recover From His Drug Addiction?

I’m starting to lose hope. My husband is addicted to pot. After months of negotiation, he finally agreed to enter a drug rehab and recieve treatment. The thing is, I don’t think any program works for him. He just finished his second treatment program and I don’t think it made any changes. He still smokes pot. Do I have to ask him to enter another drug rehab? Do I have to finally give up on him?