5000 user subscription database

We need a non-relational database to manage subscriptions of about 5000 users. It should have a simple data entry system with contact name and institution, amount paid, email address, start date, automatically calculated 1st renewal reminder date; 2nd reminder for renewal and final 'last 7 days reminder'.
Reports should automatically list all contacts that need to be emailed on due dates.
If a contact does not renew, the contact is automatically ticked off into a 'non-active' list.
We run on a windows system, but will also consider web-based system.

Full details later