Make It Ephemeral: Software Should Decay and Lose Data (pocoo.org)
Most software that exists today does not forget. Creating software that remembers is easy, but designing software that deliberately “forgets” is a bit more complex. By “forgetting,” I don't mean losing data because it wasn’t saved or losing it randomly due to bugs. I'm referring to making a deliberate design decision to discard data at a later time. This ability to forget can be an incredibly benefitial property for many applications. Most importantly software that forgets enables different user experiences.