First question......  are you sure it's a droopy eyelid and not a droopy eyebrow?  9 out of 10 times the problem is the eyebrow sagging making the upper eyelid appear heavier and more hooded.  One way to tell is to lift that eyebrow up with your finger and then look up.  If you can open your lid the whole way, then it's the eyebrow!!   When the eyebrow comes down, it's usually because there was a little too much put in the forehead or the placement of it in the forehead was too low.   Let your  doctor/provider check you to make sure.  It's easy to adjust it next time so that doesn't happen again.  My sympathies though while it's wearing off!