The invention utilizes an existing cash register that, in processing the purchases, establishes an identifier (i.e. date stamp, barcode, QR code) on the receipt. This code is then used at an exit portal to trigger the opening of a barrier allowing the purchaser to leave the building. In the preferred embodiment, an image of the customer is taken on entering and leaving the building and facial recognition is made for the purpose of later apprehension or for future denial of entry into the store.