Memoirs can be either singular or plural, depending on the context. Generally, a memoir is a single, personal account or story of a certain experience or set of experiences, usually spanning a certain period of time in someone's life. Therefore, in singular form, the word "memoir" refers to a single narrative.
In plural form, however, the word "memoirs" can refer to a collection of narratives, typically written by one single author. For example, when referring to an author's book of memoirs, "memoirs" is often used in the plural to indicate that the book is made up of multiple stories.
