When I worked at ClearChannel back in 2010, we rebuilt Rush Limbaugh's site. When migrating over the billing system, I realized a flaw that granted at least 20,000 people free access to the audio archive ($7.95/month). The billing provider processed the subscriptions, but their system would only sync with our authentication database once a week with a diff of accounts added or removed in the past 7 days. You got the first 7 days free for this reason. If this process failed (e.g. due to a connectivity issue, timeout, or SQL error), all accounts after the error would not be updated. Anyone with a free trial or people who cancelled during a week with an error would get a permanent free trial. I rewrote the code to handle errors and retry on failure so that errors wouldn't happen in the future, but my downfall was running a script that updated all accounts to the correct status. Imagine angry Rush Limbaugh fans used to getting something for free now getting cut off (even though it shouldn't have been free). Management quickly made the decision to give them free access anyway, so I rolled back the change.