Replacing Baterry

My car is a Honda Fit 2013 Sports Fit. I've had it for less than 3 weeks. I've had one accident where I backed into a ditch and I had to repair my rear bumper.

One night out I tried to start my car but the battery died...I'm not sure why but I think I possibly left my lights on when I parked my car. Luckily my friend had a jumper cable and jumped my car back to life.

Should I buy a new battery? The car is less than 3 weeks old and I'm not sure if damaging the rear bumper has anything to do with causing the battery to go out.

Thanx!

Does it still have problems starting, or was it just that one time? If it was just that one time, I wouldn't worry about it. If it's not starting now, for no legit reason, you should take it back to the dealership that you purchased it and have them check everything.

It was just once (yesterday), hopefully it doesn't happen again >.<. How does the battery work exactly? Because I thought if it died, I would need to get another one and that jumping it was just temporary?