Accurate assessment of performance is a key and challenging topic in satellite communication (SatCom) systems. Key performance indicators (KPI) include latency, availability, capacity, and flexibility. KPI are important to assess and monitor at different steps of the design, implementation, and operation of a SatCom system. An efficient concept of operations, describing the capabilities of the system and how the system should be operated is also relevant and must rely on accurate performance assessment of selected KPI. This paper proposes a common framework (MAPAN-Management and Performance of Access Networks) for performance assessment at the different phases of the system: planned performance based on theorical assessment and expected configuration, actual or effective performance based on actual measurements, and predictive performance based on actual configuration and projection of expected or desired events. A concept of operations of a live SatCom system based on the MAPAN framework is also proposed. It aims to optimize the efficiency of SatCom systems thanks to continuous adjustment of the contractible and allocable resources, based on actual and predicted system performances. The paper introduces a reference terminal for planned performances, an algorithm for performance averaging throughout a beam and real-time link budget for performance prediction.