Most process of lease is done manually in the past. Since the networks were used extensively and systems of Point of Sales risen quickly, the efficiency of administration of payment flow had been obviously promoted. What are mostly encrypted are information of payment flow, but what we encrypt is the information of leased products this time. We apply encryption technique to the lease system, and access information via RS-232 devices, such as SmartCard Reader and EM Reader. After processing of system and encryption, the system will transfer the processed data to the server. In this paper, we take Kaohsiung C-Bike Lease System for case study, our discussion will focus on network packet, data encryption, and real-time monitoring. We will also introduce critical features and mechanisms of the lease system and address some issues we encountered. This system encrypts data via Advanced Encryption Standard, sends out data packets via TCP/IP, and monitors leased bikes via databases and framework of multi-thread.