Last year I started asking my friends to use gender-neutral pronouns for me but they keep using female pronouns even though I've politely reminded them many times over the past year. Should I keep reminding them or should I just give up on trying to get them to use they/them pronouns?
Are they attempting to use them at all or just flat-out ignoring it? I'd keep reminding them and tell them why it's important for you. It's a good idea to have a proper conversation about it, rather than just keep saying "it's they/them" each time they use the wrong ones. It could be that they don't fully understand. In the end, if my friends didn't respect me and my comfort and deliberately did something that upsets me - knowing full well it upsets me - I'd start reconsidering if they were actually my friends or not.
I think you should definitely continue trying, if you want people to use they/them pronouns, they should respect that. Have your friends made any effort at all? If not, I'd explain it to them one more time - tell them how important those pronouns are to you - and if they still won't listen, I would stop being polite. I started calling one of my cis male friends by a very feminine sounding name and started using she/her pronouns when speaking to him. He was confused at first, even angry, but then he got the message and finally started using the right pronouns for me. Sure, some people need time to adjust, but others are just unwilling to make an effort.
It could be they don't think it's important enough to bother, or it could be that they honestly forget and the polite reminder isn't enough. By all means keep trying. If you haven't sat down and explained why the correct pronouns are important to you, do so. Tell them that you are uncomfortable. Being polite isn't working, so time to be blunt and insist.
