I noticed that if you lock the app, and then restart your computer, even if the app is set to run on startup it doesn't inherit the state (locked and timer count) when it starts back up. It would be nice for a shutdown to either account for time shut down (ie: if you have it locked for 10 hours and shut the PC down for 5 then 5 hours remain), or for it to simply save the countdown time remaining on shutdown, and pick up where it left off when it starts back up (ie: if 56 minutes remain on the countdown when the PC is shut down then when the app next starts it will be locked for 56 remaining minutes).
Depending on how you've coded the lock countdown this could be a huge lift, or a very simple implementation, but I figured I'd make the suggestion for the next iteration!