Other Memory is the term used by the Bene Gesserit Sisterhood to describe the well of genetic memory their Reverend Mothers possessed. Non-Bene-Gesserit users of Other Memory include Paul, Ghanima, Alia and Leto Atreides.
Other Memory was used mainly as a source of knowledge, especially when much written history had been lost to time. It was only made available to an individual after they successfully converted a Awareness spectrum narcotic. If they could not, they died.