Accessibility turns off for Applock on reboot

Norton Applock needs Accessibility to be turned ON on Android for it to function even on reboot. However as soon as the mobile is rebooted, the accessibility turns off automatically thereby rendering applock unusable. Phone info:

1) Android version: 6.0

2) Make/ model: Micromax Canvas Spark 2 Plus

3) Kernel: 3.18.19+