MarkLogic can create a new class of license. Call it the "MarkLogic Server Lite" or something like that (I don't care). It should be well trimmed down from the Standard and Enterprise editions. No geospatial support, no entity enrichment, no compartment security, etc. Put a database size limit of 1 GB and only allow it to run on 1 CPU. And make it completely free to use, even on commercial projects.
via NoSQL databases