1. A server device for managing rewards to be given to a user, comprising: a storage unit for storing a package as a set of data concerning rewards to be given to the user and a modified package as a set of data concerning rewards used to update the package; a communication unit for communicating with a user device of the user; and a package updating unit for updating the package by modifying the data concerning the rewards included in the package by using the data concerning the rewards included in the modified package when a package update request is received from the user device.