The antonyms for the phrase 'letting slip from memory' can be many such as remembering, recalling, retaining, recollecting, engraving, imprinting, etching, impressing, storing, embedding, and holding. The act of letting slip from memory refers to the unintentional or intentional forgetting of something important, and the above-mentioned antonyms signify the act of remembering or keeping something in mind. It is vital to remember things that matter, whether it is a phone number, a meeting schedule, or any significant event. By actively working on remembering things, an individual can reduce the risk of things slipping from memory, which can aid them in their personal and professional life.