The download button opens the iTunes App Store, where you
may continue the download process. You must have iTunes installed with an
active iTunes account in order to download and install the software. This
download may not be available in some countries.
From A KITCHEN:
Souvenirs enables you to travel back to the events that took place in your life exactly a year ago, by picking the photos you took on that same day a year before. Connect the app to as many of your albums as possible and let Souvenirs carry you away