How are offer and offer code usages stored?

RecordOfferUsageEventListener (a CheckoutCompletionEvent listener) is responsible for identifying the offers and offer codes used on the completed order and recording them as OfferAuditDetail records (BLC_OFFER_AUDIT_DETAIL). Note: each OfferAuditDetail record includes the dateApplied, orderId, offerId, customerId, & sharedCode (the offer code).

Later, when the offer engine is considering candidate offers, it will leverage these OfferAuditDetail records to disqualify offers and offer codes that have already met the max number of usages.