I wish I did this. Your friends only tell you the name of their kids once. If they even remember without you prompting. And then time passes, you have interactions and it's too hard to ask: "hey remember your three year old daughter I've mailed christmas presents for...what's her name again?"
Why is it too hard to ask? That's just in your head. Especially if you're honest about being bad at names and make a little joke about it, 99 out of 100 people will just laugh and tell you the name.