CSLA .NET is released under a very open and permissive license:
CSLA .NET license
If this license is not acceptible to you, Marimer LLC is willing to consider providing a custom license. In such a case you will be required to purchase the custom license. This is necessary to cover the legal and administrative costs, now and into the future, incurred by Marimer LLC in creating and working with your custom license through time.
If you need a custom license, please email rocky at lhotka.net to initiate any discussion.