Uninstalled iphoto by accident, how can i get it back for free?

Hi!

I have a macbook pro from last year, got it around march. Back then i installed all the apps you get with macbook, imovie, garageband and iphoto. I tried iPhoto, but was completely lost and i just thought that i might as well just delete the app if i don't use it, so i did. Now, that one of my friends have a macbook and use iPhoto i understand how the whole thing works, so i would like to get it back. Only problem, how? I go to app store and purchases, but it's not on the list, imovie and garageband are there though. Now i search for iPhoto in the searchbar, and it says that i need to pay for the app. So my question is, how do i get iPhoto back?

Thanks!