A method of controlling the functioning of a portable medicament dispenser, said method comprising: (a) providing a memory for storing one or more parameters relating to the functioning of said dispenser; (b) storing authentication data for authenticating data for controlling a function of said dispenser; (c) receiving control data for said dispenser; (d) performing authentication of the control data using said stored authentication data; (e) in dependence on a result of the authentication, activating one or more parameters in said memory to control functioning of said dispenser in accordance with said control data.