I am also out of my usual place right now, I use the mobile data from my phone to have internet for my laptop. And I have a data limit.
There is a setting on Android phones which warns you when it’s over.
Go to “Settings” → “Portable hotspot” → “One-time data limit”. Enable that.
Then there is:
“Size” where you write your data limit.
and
“When exceeded”. Here you have two options: “Turn off and notify” or “Only notify”