Not forget is a phrase that is commonly used to remind someone to remember something important. However, there are several other synonyms that can be used instead of not forget, such as recall, recollect, remember, retain, retain in memory, keep in mind, bear in mind, be mindful, and not overlook. Each of these synonyms has a slightly different meaning, but they all convey the same idea of reminding someone to remember something important. It is important to choose the right synonym based on the context and the desired tone. Regardless of which synonym is used, the objective is to ensure that the person remembers the important task.