Instagram is continuing its assault on Snapchat (which is working) by opening up its Stories clone to any photos and videos in your photo library. Stories were originally limited to shots and footage captured in the app, then later updated to include photos and video captured within the last 24 hours.
Removing the 24 hour restriction from Instagram Stories should encourage more users to share photos and videos with the feature, and Instagram is adding a new date sticker to Stories with images and videos captured over a day ago. The date sticker is optional but helps preserve the in-the-moment nature of Stories.