I don’t have a good memory, so I only remember the really simple ones by heart. Usually I try to understand the meaning of the equation instead, because then I can often figure out what the precise form is or look it up if necessary.
I remembered more equations during my A-levels than I do now! but i think the difference now is that i know how to derive them from first principles (well, the easy classical ones anyway, not the quantum ones) so I don’t need to memorise them.
I use equations quite a lot, but I tend to use the same ones over and over and after a while they stick in your head.