Apple has recently updated GarageBand, iMovie, Keynote, Pages, and Numbers for Mac and iOS, so that those apps are now free. Previously, those apps were free to users who bought a new Mac, iPhone, or iPad, and the free download was a one-time event. Now the apps are free all the time.
Apple has not officially announced the price changes, nor did they issue a statement to users who have recently paid for any of the apps. The free versions are now available on the iTunes Store and the Mac App Store.