The invention relates to authentication in mobile financial transactions, and more particularly, to systems, devices and methods of employing a location tracking function within a mobile device for the purpose of authenticating a user and a trusted transaction when this mobile device is configured to a mobile point-of-sale (POS) terminal. Authentication is primarily implemented by a secure element integrated within the mobile device based on comparison between captured geo-location data and some known information, such as a retailer address, this user's behavior pattern and shopping habit, that may be derived from the geo-location data. In the secure element, a secure memory stores a plurality of geo-location data from which a secure processor generates information concerning a behavior pattern or a shopping habit of the user. A V/A unit receives a real-time geo-location of the mobile device, and thereby, verifies the user or the trusted transaction according to the generated information.