Loyalty cards programs have been used by retailers to increase customer retention. Loyality cards provide means to identify a particular customer and to collect customer specific data, thus enabling individualized marketing; however, operating a loyalty program is complicated for retailers since they require to manage balances, collections, and transfers of customers. Moreover, customers may forget or even deliberately decide to not use their cards mainly because it is uncomfortable carrying a physical card. %
This paper proposes a Loyalty program based on a blockchain that does not require a physical card for identifying customers as it associates customers to their phone numbers. In this perspective, companies can reduce overhead costs involved in managing the loyalty program. This paper reviews the technology required, and describes the implementation of a loyalty program based on blockchains. Finally, it also enumerates the reasons for choosing the blockchain technology for this application.