Please don’t forget...
Use this expression to remind someone to do something.
John is going to the airport to fly to Thailand. His sister Mary tells him not to forget his passport.
John: I’m leaving for the airport.
Mary: Please don’t forget your passport.
John: Thanks, I won’t.
John often forgets to do his homework on the weekends so his mother reminds him every Friday.
Mom: John, please don’t forget to do your homework this weekend.
John: Don’t worry mom, I won’t.