My WordPress site is set to be local time which is GMT -5. When I manually edit a post to set an expiration date and time, the plugin seems to immediately compare the expiration time to GMT rather than to local time. This makes testing very difficult since I can only set expiration 5 hours later than current time. My development system is in the local time zone so I must wait 5 hours to verify that expiration works.
My test system in the time zone GMT -7. It appears that the sql code that runs to expire posts uses the local time of the server, rather than the local time of the WP site as defined in settings. So the post is expired two hours later than it should be and makes testing even more delayed.
At least this is what I infer from my testing.
I hope that the next version will correct both of the time comparisons.