I am looking into fillers because of hollowness under my eyes. How long does one session last?

The hollowness under my eyes and on my cheeks has become so severe that I've been told I look depressed. So many of my neighbors have been getting fillers lately that I've finally decided to bite the bullet and am actively researching the possibility. However, I've heard that you need to get them regularly to maintain the shape. I don't have the time to go back and forth to the dermatologist, and I absolutely hate anything that is a hassle. By the way, for someone my age, how long does the volume typically last after just one filler session? My biggest concern is that I might spend a lot of money on fillers only for them to completely collapse within a few months. I look forward to honest answers from those with experience!