There are many synonyms for the phrase "not be forgotten". Some of these include memorable, unforgettable, indelible, lasting, enduring, noteworthy, remarkable, significant, and remarkable. These words convey the sense that something is so important or impactful that it will remain in the mind of those who experience it long after it has ended. Whether it is a moment in history, a person's story, or a particularly special event, using these synonyms can add depth and emphasis to any description. So, the next time you want to talk about something that will "not be forgotten", consider using one of these alternative expressions to give it even greater weight.