Software-defined networking (SDN) enables network subscribers to negotiate QoS parameters in a on-demand basis. On the other hand, peak-time congestion accompanying the fast-growing traffic in recent years forces Internet service provider (ISP) to put forward a new pricing scheme by taking into account when a user uses Internet in addition to how much a user uses Internet. In this paper, we study the payoff optimization problem of ISP and network subscribers in SDN-enabled networks. A self-interested network subscriber always tries to obtain network resources as much as possible even if the network is congested; on the other hand, rational ISP tends to charge a higher price without providing subscribers guaranteed Quality of Service (QoS). A Stackelberg game is hence constructed to analyze the competitive interactions between ISP and home network subscribers. Specifically, ISP decides its pricing strategy for each time slot by solving a payoff optimization problem. Given the pricing strategy, network subscribers then decide the bandwidth to be reserved in a on-demand basis aiming to optimize their own payoff as well. We analyze the Nash equilibrium solution of the game. Simulation results confirm that the proposed pricing scheme can largely improve the payoff of network subscribers and ISP, compared to the usage-based pricing (UBP) scheme. Furthermore, the portion of surplus obtained by ISP increases with the increase of traffic load.