External user authentication and user based data access/permissions

We need the ability to create and share reports/dashboards with external paying clients and we need to be able to authenticate and provide row level security to these external clients outside of our AD and domain. Each external user may only subscribe to certain parts of the data - so we need to ensure they can only view the data that they actually pay for. So we need to know who is accessing the report (outside our org/AD) and then deliver the data to them based on what they subscribe too - so need a mechanism to manage this - External user based data access