Alarm Clock 3rd Party App not disabling auto lock iPhone 5

I've already contacted the developer of this app called "My Alarm Clock" about this, but wondering if there's something possibly wrong with their code or with iOS 8.3 on an iPhone 5 where the auto lock not being disabled when plugged in. I use this app as my primary alarm clock to wake up in the AM and was disappointed to learn as of late that auto lock is turning off my phone in the middle of the night and caused me to oversleep one morning. The workaround is to manually disable auto lock before going to bed, but wanted to know if there's an iOS API for whether or not an app can override the auto lock settings in iOS.

Thanks in advance!