There's a bug that a few people have run into in the last few versions (including the one that just got released a couple of days ago). When Lux is installed, you can't power off the phone. If you try, somewhere between a few seconds to a half minute after the phone looks like it turned off, it will turn right back on again. (KitKat, if it matters)
I've found only three ways of shutting off the phone fully:
1. Pull the battery.
2. Disable the Lux service before powering off.
3. Uninstall Lux.
Someone else having this bug said they've been emailing the Dev for months and never even got a reply, let alone a fix.
I know that a version only just got released, but the Dev used to be much more responsive to issues. Has he effectively given up on this app?