Accessibility services gets disabled automatically I have a Gionee p3s.  I was trying to use tasker when i observed that the tasker accessibility service gets disabled automatically after a few minutes. Not only with tasker, all apps requiring accessibility services are having the same problem.
My android version is 5.1. It will be helpful if some one can help me with this problem. :-)
I was facing the same issue on my Lenovo vibe k5. I did the followings to solve the issue.


Enable accessibility for the concerned app in the Settings.
In power saving option (in most cases it is inside the "Battery" option) select the concerned app not to be optimized.
Select the app as device administrator (this setting may be found inside "Security" option).
If possible lock the app in Task Manager so that it will not be killed when you kill all the tasks(apps). In "mi" phones you need to slide the app downward to lock it in Task Manager. I don't know how to do it in Gionee p3s. In my device this option is not available so I never kill the concerned app in the Task Manager( Or if I kill the app I re-enable the accessibility, then it remains enabled until I kill that app again).


After doing these the Accessibility option remained enabled even after restarting the phone.
This may not be the exact solution you asking for, but this is all I found after hours of searching.