Pete also helped Jesse out in the early seasons by dealing the meth Jesse was cooking, even though Pete was worried about getting caught and sent back to prison. (He'd already served time at the start of the series.) After one of his dealer friends was arrested and another was killed, Pete quit the business all together in season 2. But he was back at it in season 3, where Pete targeted Narcotics Anonymous meetings to make his sales. He gave it up when the recovery program at the meetings started to actually work on him. But then he slipped up and used meth in season 4 at Jesse's house. Most of the show was like that for him. He would want to do better, fall back into old habits, recover, revert, etc.