Memoir is a historical account or biography written from personal knowledge or special sources. The main advantage is that if the author is sincere there is a possibility that you get the correct picture (ring side view) of what happened if the person is important. But it is also possible to twist the facts and present either a glorious view.
Memoirs of other people can be amazing. But as Costas already mentioned, they contain self awareness and self asessments. These pictures must not be honest and true, but they facilitate insights in the writers personality and character.
I´m not sure, that I will write my memoirs to "survive".
Memoirs can be formal, informal or can be published, unpublished, or can be telling the family history or political events. The problem is that a few people can make memoirs because of the time pressure.
Memoire is a collection of memories that an individual writes about moments or events, both public or private that took place in the author's life. Historically, memoir has been defined as a subcategory of autobiography. people cab be honest or dishonest in their memoirs!
I am not planning on writing a memoir! but I love leading the biographies/memoirs of scientists and therefore I have not thought about the contents! but a list given by dear dear @ Debi looks very complete. there is a book (biography and not memoirs) that I have had since years ago and found it very interesting. it is a very aspiring book which I recommend
As I understand, the writing of memoir requires an examination of one's memories, a procedure of applying focus to them, such that they are revealed in ever greater detail. This can be a most enlightening and valuable process, both for the memoirist him/herself, for whom the memory otherwise tends to fade, and perhaps even for the reader, whose imagination may be enriched from engagement with another's experience. I find the words of Socrates relevant, though the context may be somewhat forced: "The unexamined life is not worth living."