In the freemium business model, how to price value-added services and design effective strategy to achieve the sustainability of value-added services promotion is of great significance to enterprises. By constructing a monopolistic freemium enterprise, this paper uses a Multinational Logit model (MNL model) to analyze value-added services pricing and two kinds of value-added services promotion strategies (the quality reduction strategy of basic product and the price discount strategy of value-added services) with heterogeneous sticky-users demand, and then discusses the optimal promotion strategy. The results show that: Both the quality reduction strategy of basic product and the price discount strategy of value-added services can have positive impacts on the profit of enterprise. The sticky users demand valuation plays a positive role in promoting the optimal profit of enterprise. The optimal promotion strategy is the price discount strategy of value-added services. This study can provide a theoretical basis and decision support for the operation and management of the freemium enterprises.