I had a very similar dilemma myself when putting together a project of mine a few months ago. However, at the end of the day, I felt that keeping the license of the solution (or core solution) as MIT was the best option irrespective, and my thoughts came from the following areas in which monetisation can be substantiated.<p>- Labor costs for staff, which include developers, network administrators, and support officers.<p>- Costs incurred for resources, server infrastructure, office resources and so fourth.<p>- And of course marketing and sales of the solution.<p>The key is to communicate this substation, therefore asking customers for donations, i feel, becomes irrelevant if you can do that effectively. So really the gist is "it's great that the software is free but someone has to run it and even more so someone has to keep supporting it".<p>Ideally, my opinion on monetisating comes from the business model which encapsulates the solution, therefore licensing the end product can just be focused around the tangibles that inherently make up the business side of a SaaS company.<p>I think the most murky part of this dilemma comes from professional services and enterprise grade solutions because this is where custom and closed treatment maybe needed for the client. Plus other issues come more from a security standpoint and trade secret standpoint than anywhere else. For instance customisation on top of a SaaS platform via APIs or integration work may require the asset (or code) to be closed source from the perspective to satisfy the clients' needs, but this has always been an issue and is not a SaaS centric problem as the argument only comes during the purchase cycle of a company and the IT manager asks the question "can our business trust open source?".