I'm not a lawyer, if you are afraid you are doing something wrong then contact a lawyer. In my opinion each user is consider the public so you can use freely. Google Maps does not want someone making like a vending type machine and charge for each time a person views / prints a map without paying them. Several software solutions charge per transaction for different services that their software provides for example, tax software charge for efile, credit bureau interface for each report, and text message send from computer. Software companies charge like 5 cents per transaction and this is just for the access from your main software, not including what the service actually cost.