A computer-implemented method for enforcing advertisement viewing executed by a Digital Rights Management, DRM, agent in a multimedia device , comprising the steps of: a. receiving, by a DRM content processing engine, DCPE, of the DRM agent , a request to play contents from a multimedia player of the multimedia device ; performing by a rights manager, RM, of the DRM agent steps b-h: b. receiving (step 805) a content key request for decrypting contents, from the DCPE ; c. detecting (step 810) a rights object, RO, of the contents; d. determining (step 815) whether the detected RO comprises a parent RO that can be applied in common to the contents; e. if the detected RO comprises the parent RO, determining that an advertisement should be transmitted to the multimedia player before playing the content by detecting a requirement element in the parent RO, the requirement element defining at least one advertisement playing method (steps 820 and 825), f. selecting (step 835) the advertisement in the requirement element, transmitting (step 840) to the DCPE an identifier of the advertisement to be rendered at the multimedia player and an advertisement key for playing the advertisement, converting to an enforcement state (step 845) to enforce the advertisement for a predetermined play enforcement duration, and receiving (step 850) a further request from the DCPE for access rights of the contents and the content key; g. in absence of the requirement element in the parent RO, determining (step 825) that an advertisement need not be transmitted before playing the contents, and h. providing (step 830) the content key to the DCPE for decrypting the contents; i. decrypting the contents with the key by the DCPE, j. transmitting, by the DCPE, decrypted content to the multimedia player. a. receiving, by a DRM content processing engine, DCPE, of the DRM agent , a request to play contents from a multimedia player of the multimedia device ; b. receiving (step 805) a content key request for decrypting contents, from the DCPE ; c. detecting (step 810) a rights object, RO, of the contents; d. determining (step 815) whether the detected RO comprises a parent RO that can be applied in common to the contents; e. if the detected RO comprises the parent RO, determining that an advertisement should be transmitted to the multimedia player before playing the content by detecting a requirement element in the parent RO, the requirement element defining at least one advertisement playing method (steps 820 and 825), f. selecting (step 835) the advertisement in the requirement element, transmitting (step 840) to the DCPE an identifier of the advertisement to be rendered at the multimedia player and an advertisement key for playing the advertisement, converting to an enforcement state (step 845) to enforce the advertisement for a predetermined play enforcement duration, and receiving (step 850) a further request from the DCPE for access rights of the contents and the content key; g. in absence of the requirement element in the parent RO, determining (step 825) that an advertisement need not be transmitted before playing the contents, and h. providing (step 830) the content key to the DCPE for decrypting the contents; i. decrypting the contents with the key by the DCPE, j. transmitting, by the DCPE, decrypted content to the multimedia player. <EOS>