Facing a serious piracy problem, some digital product manufacturers do not implement a strong DRM (digital rights management) restriction into their products, the authorities also do not give a high priority against piracy. In this paper, we develop a theoretical model to investigate pricing strategies and optimal piracy control level of a digital product monopolist by incorporating DRM protection level and copyright enforcement by the government into this model. In our model, if the DRM protection level rises, then the consumer’s valuation for the legal product will drop and the pirate cost of the illegal product will rise. Further, we use following two variables to evaluate the copyright enforcement by the government: the probability of the illegal users are caught by the authority and the fine if they are caught. Our results show that DRM-free strategy is the monopolist’s optimal choice under the condition that the copyright enforcement by the government is sufficiently high; otherwise, the monopolist should choose a right DRM protection level to curb piracy. We also find that a moderate copyright enforcement is welcome to the monopolist and the consumers, and it can maximize the consumer surplus and the social welfare.

面对严重的盗版问题，一些数字产品制造商没有对其产品实施强大的DRM（数字版权管理）限制，当局也没有对盗版给予高度重视。在本文中，我们通过将 DRM 保护水平和政府的版权执法纳入该模型，开发了一个理论模型来研究数字产品垄断者的定价策略和最佳盗版控制水平。在我们的模型中，如果 DRM 保护级别上升，那么消费者对合法产品的评价就会下降，非法产品的盗版成本就会上升。此外，我们使用以下两个变量来评估政府的版权执法：非法用户被当局抓获的概率和被抓到的罚款。我们的结果表明，在政府的版权执法力度足够高的情况下，无DRM策略是垄断者的最优选择；否则，垄断者应该选择正确的 DRM 保护级别来遏制盗版。我们还发现适度的版权执法受到垄断者和消费者的欢迎，它可以最大化消费者剩余和社会福利。