i remember reading a fic like 50 First Dates.i don't remember if it finished...i only read four chapter so far.

I couldn't find a buffy one with short term but there is this one with spike with short term and based on 50 first dates.

From That Dream's Apocalypse by OffYourBird

There's 3 chapters available.

The tags for the fix says, «Themes stolen unapologetically from 50 First dates.»

Summary
Spike wakes every morning in a room he doesn't recognize, and nothing about his world is ever quite the way his mind tells him it should be. Not to mention the woman always nearby—Buffy, the Slayer, his jailer, a stranger, a lady—a beautiful image from a dream he can't remember

https://archiveofourown.org/works/42813417