Yes, let him know. Circle the date on the calendar with giant red heart. Mention it maybe once a week. A lot of men, myself included, have terrible memories for this kind of thing. I can remember a birthday of someone close every day for a month and then I forget completely right before. I feel like a shmuck. It doesn't mean we don't care. Also, some people grew up in families where birthdays and anniversaries were a big deal. Others not so much. I personally love it when a woman helps me out like that. It tells me she can communicate to me openly and maturely about her needs in the relationship. I absolutely hate it when they say nothing to test me to prove whether I really love them. Passive/aggressive b.s. Mind you, don't bring it up every minute of every day. That is what the calendar is for. If he knows you really care about it, then he should care about it too. He just might need some help along the way.