What is the reason behind having a different database for each client? You can ensure security by applying XPath constraints on your entities, so that a client may only access their data.
You may want to use a Database connector to bring in an external database which can be used to store customer specific data: https://marketplace.mendix.com/link/component/2888
Perhaps a multi-tenant architecture might suit your needs better, depending on your requirements: https://forum.mendix.com/link/questions/104331 . But most of the time, properly structured domain model with XPath security would do the trick
Thx for your help.
What kind of license should i use in this case? Basic is enough?