I meet girls on the middle of the day in plain day light and talked to them for a bit.
1-2 hours later I completly forgot their name.
Happened to me yesterday. Meet a really good looking Iranian woman (around the age of 35+). She said she just had moved to south Florida from Nebraska and that she isnt used to the heat. She looked European to me, like east European, cuz she was white with blonde hair with bold red lipstick.
Happens to me often, I meet hot milfs too and we have a cool conversion, and I blank out later. Then I see them again, they say "Hi Ricky" and im like "Hey... how are you Miss."
I've noticed that I generally have a hard time remembering peoples name if all they give me is their first name. I tend to remember your name right away and for longer if they give me their full name. So when I meet people I I tend to ask for their last name too, except not all occasions is alright to ask for their full name when you just met them.
Ask her how to spell it, or tell her some story that fits the situation about how her name wasn't added to your contacts and you want to be sure it's spelled right. The worst thing she can say is "the usual way" in which case you're screwed, but most people will spell it for you.