While location flexibility addresses spatial constraints, user-identity flexibility through data trading creates new economic opportunities by enabling peer-to-peer resource sharing. In this chapter, we focus on the data-trading service, and analyze mobile MUs’ optimal trading strategy and the MNO’s revenue-maximizing trading prices. Moreover, we will also investigate how the rollover data service affects the equilibrium between mobile MUs and the MNO. This chapter will unveil the economic viability of integrating time flexibility and user-identity flexibility.