Is the 'aqiqah obligatory upon the parents if the seventh day has passed and they are able to perform it later, or upon the child when he grows up, or is it not permissible after the seventh day?

The 'Aqeeqah is a Sunnah and not obligatory. The father is responsible for it, and it is slaughtered on the seventh, fourteenth, or twenty-first day, or at any time thereafter. If the 'Aqeeqah was not performed for a child, it is recommended for him to perform it for himself after puberty if he is able to. It is recommended to borrow its cost for one who can repay it, and it is not disliked for the child to perform the 'Aqeeqah for himself when he grows up.