A memoir is a subclassification of autobiography, typically limited to a small period or critical moment of the author's life.
History and specifics[]
The Klingon warrior B'ator, member of the House of Gorm, fought in the final battle of a conflict, which he later wrote about in his memoirs, claiming to have maintained warp 8.1 for three days in a Klingon bird of prey. (ST novel: Engines of Destiny)