A retail vendor application installed on a user device receives configuration parameters for a user interface button that can be used by a user of the device to purchase an item available for consumption. The application determines, based at least in part on the configuration parameters, an activity trigger that, if detected, causes the application to present the button to the user. The application monitors sensors and applications on the user device to obtain data that can be used to detect the activity trigger. In response to detection of the activity trigger, the application updates an interface of the user device to present the button. If the user selects the button, the application generates a purchase request for the item that is sent to a retail vendor service for processing.