Plan B pill

I’m single, and I slept with my friend on Saturday night/Sunday morning cuz it was around 2am when I went over his house. So we ended up doing it without a condom. I didn’t buy this plan b pill until today in the evening. I know it says that you can take it up to 72 hours of unprotected sex. What do you ladies think about this pill and have there been success that it actually works