It is based on Tokyo Cabinet (which is under LGPL).
On the homepage of Tokyo Cabinet, it says:
"BTW, do you know Kyoto Cabinet? Actually, it is more powerful and convenient library than Tokyo Cabinet. At this distance of time, Kyoto Cabinet surpasses Tokyo Cabinet in every aspects. I strongly recommend you to use Kyoto Cabinet."
I wonder why that isn't used. Maybe because Kyoto Cabinet is under GPL.
Indeed, this is probably the reason. The company that developed ejdb (Softmotions) apparently uses ejdb in their own proprietary software, and they wouldn't be able to if it contained any GPL components.
On the homepage of Tokyo Cabinet, it says:
"BTW, do you know Kyoto Cabinet? Actually, it is more powerful and convenient library than Tokyo Cabinet. At this distance of time, Kyoto Cabinet surpasses Tokyo Cabinet in every aspects. I strongly recommend you to use Kyoto Cabinet."
I wonder why that isn't used. Maybe because Kyoto Cabinet is under GPL.