I had sex and we used protection, when we finished i felt something was liking on my legs, i think it was semen, should i take the pill?

Semen: can leak from a condom. I would suggest a home pregnancy test within the week and also, using condoms PLUS spermicidal foam, jelly, sponge or vaginal suppositories.

NO idea: If you want to be sure, then you might. What kind of protection did you use and where were you in your cycle ? These are all things that might make some difference. If you used vaginal foam then you may not need to worry. If it were a condom and ruptured then you might use plan b. Best wishes.