You will be remembered if you would do that one little thing. When you RSVP to invitations and thank people for the gift that you received from them, you ARE remembered. When you say “thank you” the next time you see them, that could be a month or longer. Inexcusable! In etiquette behavior, you should respond ASAP within 10 days. I remember the people that never thanked me by writing a small TY note for the wedding gifts, baby gifts or house warming gifts that’s been given over the years.