The licensing is strange as well. The BSD license is listed as a feature, but the embedded scripting language (Jx9) is SPL (their own GPL-alike/Sleepycat license).
Since the Jx9 language is fully embedded (even stated as " All C source code for UnQLite and Jx9 are combined into a single source file."), they seem to contradicting their own licensing. The resulting library would also retain the copyleft SPL license.
The base code may be BSD, but incorporating the whole database into your code infects it with their SPL too.
From UnQLite core developer:
No, Jx9 (the standalone library) is under SPL, while UnQLite is 2-clause BSD (including the Jx9 core), so there is no worry about that since the two software are developed by the same company. In other words, use UnQLite without restrictions
Since the Jx9 language is fully embedded (even stated as " All C source code for UnQLite and Jx9 are combined into a single source file."), they seem to contradicting their own licensing. The resulting library would also retain the copyleft SPL license.
The base code may be BSD, but incorporating the whole database into your code infects it with their SPL too.