The present invention relates to a recording unit arranged to be connected to a medicament delivery device, which recording unit comprises a generally elongated housing (10; 90) having dimensions so as to enclose at least a distal part of the medicament delivery device (50), the recording unit comprising a recording mechanism (60; 120) provided with an electronic circuit (64; 134) and arranged at a distal end inside said housing, said electronic circuit comprising an activation element (40; 108) operably arranged to activate said electronic circuit (64; 134) when said medicament delivery device is inserted in said housing, said electronic circuit (64; 134) comprising sensor elements (80; 140) capable of sensing status changes of said medicament delivery device during use.