The 0.9.x version does not work with FreeBSD or any other OS that isn't listed in org.lmdbjava.TargetName#resolveOs because that method throws an exception if it does not recognise the OS.
That method is only used to resolve the "bundled" libraries, so if it did't throw an exception (such as simply returning "unknown") then 0.9.x would work fine as long as the lmdbjava.native.lib property is set correctly (just needs to be set to "lmdb", since installing the correct port will put liblmdb.so in the standard library path)

Note that 0.8.x has always worked with FreeBSD without having to set any properties.