Ameoba is a database for component-entity systems. It's geared towards simplistic use-cases and is not meant to act a full DBMS.
It is not a relational database (RDBM), not an object-oriented DB (OODBMS), and not a key-value database.
It is a component-entity system database (CESDB). This a completely invented term because the other two didn't really fit the design.
Amoeba is dual licensed as public domain and WTFPL (for where public domain is not recognized).