Welcome to e health forum.
FYI, Pregnancy can occur, only when ejaculation occurs within the vagina, and when the woman is within the fertile period of your cycle. This period is from day 12 to day 16 of a 28 day menstrual cycle.
Having sex in the days out of this fertile period (that is day 1 to 11 & 17 - 28 ) would be less likely to result in pregnancy, and it is considered to be the Safe period.
In your case, the timing of your intercourse falls within the safe period, and there was no risk of pregnancy. Hence there was no need to use the emergency contraceptive.
Taking emergency contraceptive pills should be only in case, when you are supposed to be in this unsafe period. Taking the pill outside of this period does not provide any use, but can cause side effects like change in menstrual bleeding patterns.
I hope this helps.