5G systems will provide a flexible charging capabilities including policy control based on spending limits for a subscription. Edge computing possesses the potential for exposing policy control and charging capabilities to third party applications close to the end users. In this paper, we propose a new mobile edge service that provides open access to functions related to monitoring the usage limits regardless the way of measurement i.e. monetary, volume, duration, etc. Currently, this function is a part of the core network functionality. Using the proposed service interfaces, an intended application may track the usage of network resource by a subscriber and to request applying of enforcement action to user traffic such as quality of service downgrade, traffic redirection or blocking close to the end user. The description of the proposed mobile edge service is provided in form of typical use cases, data model, interface definition, and formally verified state models
