Returns the credentials (API keys) that calls in the date range were metered under, as id and name pairs. The id is the credential's id, or "default" for calls metered under no credential (no API key); it is not the key itself. The name is the credential's name, with the id added when the name is blank or shared. If the team has more credentials than the limit, the costliest are returned. The date range defaults to the last 24 hours.