お忘れなく
to forget oneself―lose oneself (in admiration)―be lost (in admiration)―be absorbed (in study)―be engrossed (in one's business)―be beside oneself (with joy or grief)
will never forget
ゆめ忘るな
to be forgotten―pass out of mind―pass out of one's memory―fade from one's memory―escape one's memory―slip one's memory―fall into oblivion―be buried in oblivion
to forget something
You are ever present to my mind.
You must not forget.
the degree to which something is difficult to forget
思い出さずに
Be ever present to your mind
忘れちまえ!