You can use the app across all your iOS devices with single purchase. Do not purchase for each devices. Those days is universal app
One of the best feature it having is that you can tag image to tap and hold an any point of the image. if you have a group picture, tap and hold each person and tag their name on the picture
Those day offers Journal function that seems to be simple journal app like another but it takes weather automatically and let you express your mode with cute smileys
Take your photo and post it on a decade later birthday, and 10 years after remember your 10 years ago.