I often use the android app with offline mode for several days/weeks because I don’t have access to internet. Several time I was locked out of the app and I couldn’t use it anymore. I had to wait to have an internet connection to log in again. If I understand it well you lock out the app after 30 days or so. I understand you are doing this for security purpose but this make your app unreliable for users who don’t have regular access to internet.
At the very least you should add a warning “the app will lock you out in 5 days, unless you lock out/in again”.
A better solution would be to add a setting “never lock me out”. That way users who don’t have access to internet for a month or more can be sure that they can save data in your app without having to worry that they may not have access to it just because the app lock them out.