According to a message being displayed on the app, which was only available for iOS, it will no longer be supported as of July 29th. "We know that Paper really resonated with you -- the people who used it," reads the farewell message on Paper, "so we've tried to take the best aspects of it and incorporate them into the main Facebook app."
In other words, thank you for using it, but it's time to go back to the real Facebook app.
Thank you for using Paper
In 2014 we launched Paper, a standalone app designed to give people a new way to explore and share stories from friends and the sources they care about. Today we're announcing that we are ending support for the app and users will no longer be able to log into the app after July 29.
We know that Paper really resonated with you--the people who used it--so we've tried to take the best aspects of it and incorporate them into the main Facebook app. For example, the same team that built Paper also built Instant Articles—a fast and interactive experience for reading articles in News Feed—using many of the same tools, design elements, and fundamental ideas as Paper. Our goal with Paper was to explore new immersive, interactive design elements for reading and interacting with content on Facebook, and we learned how important these elements are in giving people an engaging experience.
We know not all the features you love will move over to Facebook, but we hope you'll continue to notice elements from Paper improving the Facebook experience for everyone. We can't thank you enough for using the app and exploring Paper with us over the past couple of years.
-The Paper team