Sleepy Cat Software, the makers of Berkeley DB, went on with a fully open-source model for 10 years until getting acquired by Oracle in 2006. They however start

Sleepy Cat Software, the makers of Berkeley DB, went on with a fully open-source model for 10 years until getting acquired by Oracle in 2006. They however started the company around an existing open-source product, so it may or may not be relevant to your case. [0] https://en.wikipedia.org/wiki/Berkeley_DB https://en.wikipedia.org/wiki/Berkeley_DB