Replace one of your API keys with a new secret

Issues a replacement key and revokes the old one. This is the answer to a leaked or lost key: the new secret is returned once, the old secret stops working immediately, and the label carries over unless you supply a new one. The replacement is issued at your account's current allowance — your paid plan if you have one — not at the old key's. Rotating does not count against the active-key limit, because it replaces rather than adds. Free, and it works while you are out of quota.