I dunno. It seems like I've read a story like this a hundred times before.
That isn't a joke about the premise. It's just that "recurring memory loop" has been done a lot before, not just on these sites, and this a pretty textbook example.
Also, what happens to the letter in his hand? Even if he loses his ability to create new memories, he could still just look at the letter again, right? Eventually he'd be buried under a mountain of paper, otherwise, and he'd probably be distracted from the experiment long enough to start a new loop of trying to discover why this enormous pile of letters has suddenly appeared, until the effects wear off.
