i realise dis is ridiculously foolish of me but i just have to ask....

i had unprotected sex on august 10th. i kno morning after pills are recommended to be taken within 72 hours of having sex, so if I decide to take them now (which is like, what, one week after the incident...) is there even a point? do these pills only work if you take it within the 72 hours? any advice on dis matter is much appreciated!