In the last years, with the fast evolution of the new generation networks and services (NGN/NGS) the user-centric approach has evolved. Nowadays, the user aims to personalize his service. Providers should therefore offer service personalization and also guarantee an end-to-end QoS that take into consideration the user's heterogeneous and mobile context. In this paper, we propose a user-centric and QoS-based service session that overcomes the aforementioned challenges through several mechanisms. First, we ensure service personalization by using a service composition based on exposable services. Second, we surpass mobility by proposing a seamless service session that offers service continuity. In fact, we address the issue of service session creation according to the functional and non-functional (QoS) requirements. Finally, we take into consideration the management of the user-centric session to ensure end-to-end service continuity according to the user's requirements and preferences during the session mobility.