User adoption is the most important factor for the success of any SaaS application.  The development of ecosystem would include developing user management, billing / pricing, account management and user based access controls.  Building programs to track product usage will help you in measuring user adoption, test potential features and spot potential problem areas.

Developing the ecosystem will definitely take a considerable amount of your development time. In case you are planning to utilize a third party application, then it definitely requires an investment. Investing in developing or integrating a good ecosystem is well worth the effort as it helps increase the user subscription base.