Water meter still spinning even after shutting off water to house?
I had a rental house a number of years ago that I bought and when I bought it there was a leak in the pipe between the meter and the house and it wasn't disclosed.
You should have a shutoff valve on the house, if it's functional, turn it off and see if the meter stops. If it doesn't stop you've got a leak between the meter and the house.
I also agree with Harper, fixing toilets is cheap and easy and will save on your water bill.