Isn't it great that technology is making it easier to go paperless?!
Sometimes, I change, or add to the name of the pdf, so it makes it easier to find later - i.e. identifying information such as "Churn Dash" if it's a variation of such, etc.
Using the Search function on your computer makes it easier to find files that you can't remember where you saved them. I use "Spotlight" on my mac, and love how easy finding files is with that feature.