I'm using a prepaid card and there's no billing cycle.
How can I disable the data usage tracker from auto-resetting?
Android Oreo you cannot disable the billing cycle from the
Settings. However, there is an application, which monitors all the data you use, but unfortunately, recently it became
Samsung exclusive. I'm talking about Samsung Max (previously known as Opera Max). I've tried other apps for mobile data monitoring, but only this one could show a custom cycle. If you don't own a
Samsung you can try the Play Store for apps, which also offer the monitoring you're looking for, and share your results here :)