Keep crash report of app in the device for many days

Hi everyone,

I am new on developing android app and i have a problem.

I have developed and app for restaurant order in android studio, which communicates wit an Apache server to get the dishes, dish categories, available tables, receipts and etc.
I use php to get the data from the mysql and to store data from the tablet (Android 5, Lenovo TAB 3 710F 7" ESSENTIAL).
For me everything worked ok, in the emulator as well as in the tabet.

I gave this app to an restaurant and they tell me that the app crashes some time, without giving any error notification, it say just that the app crashed and will restart.
All the system works offline, without internet, just a local network.

Now he question is, is there any way to keep somehow crash report in the tablet and in the end after some day to get them ?????
I find out that in logcat i can get the crash report if i get it exactly after the crash, the problem is that i cannot be there to get the logcat file in that moment.

Please any help

Thank you in advance