1. A system to associate a tab of a particular customer at a particular business establishment to a payment method associated with said customer, the system comprising: an application for smartphones of a plurality of customers, said application, when implemented on a smartphone of a particular customer, said smartphone having a GPS device, said application at least to determine the geo-location of said particular customer with said GPS device and to identify from said geo-location a particular business establishment where said particular customer is currently visiting and to display a unique code; an application for a POS terminal for a business establishment, said POS terminal application comprising; an associator to associate a received code with one of a plurality of open tabs of ongoing purchases stored in said POS terminal; and an abandoned tab detector to generate an abandoned tab indication if, after the expiration of a predefined time period, that said customer has abandoned said purchase tab without paying for the accumulated purchased items; and a server accessible to multiple business establishments and accessible to said applications for smartphones, the server comprising: a customer profile database to store pre-authorized electronic payment methods pre-authorized by said plurality of customers and a purchase history segment to store data of items previously purchased by said customer in multiple business establishments; an associator module (a) to receive a wireless message from said application for said smartphone that said particular customer is visiting said particular business establishment, (b) in response to receiving the message, to generate a unique code, which is a function at least of said particular customer and said particular business establishment, (c) to transmit said unique code to said smartphone; (d) to receive an association of said unique code from said POS terminal application with said open tab, and (e) to receive a wireless communication signal from said smartphone application indicating a customer command (A) to close said purchase tab and (B) to automatically pay for accumulated purchased items by using said pre-authorized electronic payment method; a module to receive said abandoned tab indication from said abandoned tab detector, and, in response, to instruct said associator module to automatically close said purchase tab and to initiate electronic payment to said business establishment from said pre-authorized electronic payment method; and an item recommendation module to analyze said data of items previously purchased by said customer during a previous visit to another business establishment and to identify an item available in said present business establishment preferred by said customer and to send a recommendation message to POS terminal indicating that said item is preferred by said customer.