Memory cells made with comparators lose their signal state when you close and reopen a world. This is not obvious though, because they are drawn as if they retained their signal state up to any device which measures the signal state such as a repeater or a redstone lamp. The comparators and redstone which comprise the memory cell as well as all redstone leading away from the memory cell continue to appear as if the signal state is still as it was.

I tested the behavior on the Minecraft PC, which, in contrast, retains the signal state as expected.