How can I fix this indentation on my upper lip? (Photo)

That is a common fold that starts to occur as we age. As we age, essentially the fat from the upper face starts to drift gradually causing the lines around the mouth and or mid/lower face area to show up. A filler in cheek area and/or to naso-labial folds will help put things back to where it was by lifting or filling in the tissues. I would start in the cheeks first working my way down seeing what is needed. A natural way to increase our collagen, in which we lose overtime causing the fall in our skin, is by performing Micro-needling with PRP (platelet-rich plasma). This will help improve the elasticity and skin thickness that is lost. It also helps with fine lines, wrinkles, skin texture, large pores, sun-damaged skin, acne, acne scars and give an overall healthier appearance to your skin. You will want 3 to 6 treatments every 4 to 6 weeks for optimal results.

Thank you for the picture.  There are a few ways you can address this indentation or lax area.  You could certainly have an injector look at the area and consider filler or PRP with microneedling.  In my practice, I offer a series of lasers based on the skintype and once completed then we reassess for PRP and microneedling.

This can be improved with a combination of lasers, microneedling/prp and fillers. I recommend getting a formal evaluation with a cosmetic dermatologist. Best, Dr. Emer.