The development of unmanned aerial vehicle (UAV)-enabled wireless power transfer (WPT) networks has opened up new possibilities for enabling sustained power delivery to all ground devices (GDs). By leveraging the mobility and controllability of UAVs, these networks can provide continuous charging to devices in remote or difficult-to-access areas. This chapter explores a novel design for UAV-assisted WPT networks, where the UAV periodically recharges devices while returning to a fixed landing position between working cycles. We begin with the assumption that only the initial remaining network lifetime (RNL) is known, without additional updates on the network’s lifespan. We then focus on a sustainable design aimed at minimizing the average UAV consumed power while ensuring the network’s sustainability. Moreover, to mitigate the impact of the initial RNL, we further introduce the transition-based sustainable design. This approach incorporates a transitional phase aimed at enhancing the RNL, during which the UAV adjusts its operations in each task period. After transitions, the network shifts to a steady state and operates in a periodic manner, similar to the first design. Finally, we verify the sustainable performance and effectiveness of both designs in simulations.