A system (100) comprising a plurality of interconnected devices (101-105) and being arranged to provide the devices (101-105) conditional access to protected content items, characterized in that the system (100) is arranged to restrict the number of simultaneous sessions involving said protected content items to a predetermined total limit. Preferably the system (100) restricts the number of content items that can be accessed simultaneously to the predetermined limit. Security modules (300) such as smart cards can be used for this purpose. Each security module (300) may be arranged to restrict the number of content items to which it provides access simultaneously to an individual limit, which can change over time. The system restricts the sum of the individual limits to the predetermined total limit. If the limit is reached, further sessions may be refused or allowed at reduced quality level.