Cap what Auditor spends, each month and on each pull request
Set a monthly cap and a cap per pull request under Spending on the Auditor page's Reviews tab. Once one is reached, new reviews are skipped with a neutral check run that says which cap and links to raise it, so a busy repository or a bot opening pull requests can't run up a surprise bill.
The monthly cap is a budget on Auditor's own project: every Auditor request is checked against it, across reviews, theme docs and theme previews, and billing contacts get the usual budget alerts as it fills. Reviews start again on the 1st (UTC).
The pull request cap counts what Auditor has charged on that pull request and is checked before each review starts, so a review that starts under it runs to the end. A repository can override it.
More in Auditor: Spend caps.