The Eternity Perpetual Company of planet Umbeka created products so longlasting that the company went out of business.
The company produced the everlasting power generators used in miniscopes, (TV: Carnival of Monsters) the Promethean Everlasting Matches used by the Doctor (PROSE: The Cabinet of Light) and the cosmic radiation batteries used in Super Lucky Romance Cameras. (PROSE: Borrowed Time) According to River Song, their batteries "last[ed] forever". (AUDIO: Peepshow)