21. A licence holder must,(1) without delay, notify the Commission of any change in any of the information or documents required for the issue or for the maintenance of a licence and any change in the licence holder’s situation that is likely to affect the validity of the licence, in particular in the case of a change of respondent;
(2) reply within the time period and according to the terms set by the Commission to any request pertaining to the information and documents sent to the Commission;
(3) display the licence or a reproduction of the licence so that it is clearly legible, in a conspicuous place in each of its establishments; and
(4) indicate the licence number on every document commonly used as part of the activities or for advertisement purposes, in particular on invoices, contracts and websites.