Reminds me of an old Kim Stanley Robinson SF novel called Icehenge, which as I remember it revolves around life extension without corresponding memory preservation, so that history becomes a way of understanding your own past. I think it did interesting things with the unreliable-narrator trope and the idea of historical revisionism.
Definitely recommended, and I'm feeling a strong urge to dig it out and reread it; it's been decades. It'd be pleasingly appropriate to discover that I'm misremembering or have a drastically different response to it this time.
You might also give "Dancing With Eternity" a try by John Patrick Lowrie. It has a similar idea, but instead of total memory loss it's selective, and an individual can choose what they keep. I'm not done with it yet, but it does have some very interesting ideas and musings about what happens when death stops being a factor in life, or what if the process were more expensive than most could afford.
You might also like 'Soldier in the Mist' by Gene Wolfe, about a greek soldier who loses his short term memory from an injury. He starts each day by reading the journal he finds beside his bed..
I tried that not long after reading Icehenge, but didn't really get on with it. Again, that was decades ago, so maybe I should give it another look. Gene Wolfe does tend to reward older readers; I'm pretty sure most of his Urth books whooshed right over my head as a teenager.
Definitely recommended, and I'm feeling a strong urge to dig it out and reread it; it's been decades. It'd be pleasingly appropriate to discover that I'm misremembering or have a drastically different response to it this time.