DACS 1.4 is released under an open source license and commercial licenses. That is, we use dual licensing. In a nutshell, if you distribute a product based on DACS, either that product must be open source or you must obtain a commercial license from DSS (see Selling Exceptions by RMS). If you are only using DACS and not redistributing it, then you do not require a commercial license. Whether or not you are selling products or services based on DACS is not relevant.
Put another way, if you simply want to use DACS, please go ahead. If you are distributing an open source package that includes DACS, that is probably fine. But if you want to distribute a package to others that is not open source that includes DACS, you probably require a commercial license from DSS.
Please refer to the license for details.
The open source license is essentially the same as the Sleepycat license (also known as the Open Source License for Oracle Berkeley DB, Berkeley Database License, and the Sleepycat Software Product License), an OSI-approved license used for Berkeley DB that is GPL compatible.
If our open source license is unsuitable for your project, or if you have any questions, please feel free to contact us. We may be able to issue a license to you that has more satisfactory terms.
If you think that someone may not be honouring the terms of the DACS open source license, or someone other than DSS is distributing it under some other license, please let us know.