I'm currently working on a world concept that revolves around an island, let's call it Amnesia, that is basically under siege by an all powerful malevolent force, let's call it BrainDamage. The idea is basically that BrainDamage periodically wipes the memory of the island's inhabitants and completely resets the society. The inhabitants of the island are unaware of any world outside their island, as well. BrainDamage's motives have not yet been fully fleshed out but I'm leaning toward BrainDamage using the inhabitants of the island as sustenance, harvesting and consuming their memories when he resets their world.
Each time the society is reset, I'm envisioning that everyone will wake up in neutral clothing, all the signs of all the shops are erased, etc. My question, then, is how can I be sure to prevent a 50 First Dates-esque occurrence without significantly hampering society? Things like "no history books" would prevent that society from being rich and cultural, I'm afraid. For all intents and purposes, let's say that BrainDamage gets more sustenance if he consumes richer, more well rounded memories.
Bonus points if your answer can also include some options for how a certain select few individuals can "circumvent" this total wipe and allow for a 50 First Dates experience while society at large still get's zapped.
If it helps with the theme, I'm designing this world for use in a D&D game though I'd like the answers to be largely free from specific rules.
Unfortunately, like this world the bonus points are made up. (:
Edit: 50 First Dates is a movie in which Drew Barrymore has some crazy mental disorder where every day she wakes up is a specific day in her past and she doesn't remember anything after that day. Adam Sandler falls in love with her and to get her to remember him he creates a video explaining everything that she watches each morning.