Database Browser is a great add-on for Commercial, Educational  as well as Non-Profit organisations. 

Basic features of "Database Browser" is always FREE.

Advanced features and enhanced quota are available as paid plans.

Usage and Quota

Usage is measured with number of transactions performed by the user.

Transaction is successful execution of a query or insert or update on a database. Scheduled executions are also counted as transactions.

Result records is the number of records returned from any query.

Quota is based on the plan that user chooses. Choose appropriate plan below as per your need.