Here you go:
https://www.youtube.com/watch?v=oeNDl9QIt7Iand also the episode on how to get clean again:
https://www.youtube.com/watch?v=GX6IeL6hvb4But it's not that hard actually:
You take a drug, after 11-Addiction Rating weeks you have to make an addiction test. Every week you don't take the drug the test gets easier by one. If it reaches zero you pass the test automatically
Now if you do take the drug again before that the counter is reset and you have to make the test at the full or only slightly reduced threshold.
It's important to note that you have to make a check for every instance of taking a drug. It's just delayed by a few weeks.
Taking Jazz would therefore mean 11-8= 3 weeks= 21 days that you have to stay clean to not make an addiction test. If at day 15 after your last use, you take another hit, you now have to make a test at day 21 vs. the full Threshold of 3. If you had taken it at day 14 (and not again before day 21) you'd only made it against Threshold 2 since you stayed one week sober.