One of my Eyelids Droops, Especially when I Am Tired or Towards the End of the Day? (photo)

The muscle which opens you left upper eyelid may be starting to slip from its attachments. This causes the eyelid to droop and causes the eyelid crease to weaken and migrate upward (which looks like is happening in your photos). This problem is commonly worse toward the end of the day or when you are tired or have a few drinks. See an oculoplastic surgeon for an examination and possible treatment.

There are some medical conditions that can cause eyelids to droop and some of these conditions could cause the problem to worsen when you are tired or at the end of the day.  I would first consult with your medical doctor to rule out any such issue before determining any possible treatments.