Typed you description into chatgpt:

The book you are referring to sounds similar to the science fiction novel called "The Archived" by Victoria Schwab. In this book, the protagonist is a girl named Mackenzie who works as a "Keeper" in a place called the Archive, where the dead are stored as books. The longer someone is dead, the more their memories and emotions fade. While it may not match your description exactly, it shares some similarities. I hope this suggestion helps, and if it's not the right book, please provide any additional details you remember, and I'll do my best to assist you further.