Merchant Support Questions & Answers Is STAN unique? STAN is a 6-digit number that is unique only for 24 hours after purchase. Therefore, STAN + date (timestamp) is unique. Last Updated: 2 years ago in Questions & Answers Did this article answer your question? Related Articles Brand and logo guidelines for supported payment methods What is Open Banking? What is a processing account? What is EMV 3DS? What is PSD2? What is SCA?