How it works: The software owner (usually a company or individual owning all the code IP) releases the software under an open source license (often a strong copyleft like GPL) and simultaneously offers a separate proprietary license to customers who want to use the software in ways the open license would not allow​. If you are the service provider and are deciding on a license for your code: sometimes companies choose not to open source at all (keeping it proprietary) or use a source-available but not open license. If you are the service provider and are deciding on a license for your code: sometimes companies choose not to open source at all (keeping it proprietary) or use a source-available but not open license.