Last week, Elastic announced they will change their software licensing strategy, and will not release new versions of Elasticsearch and Kibana under the Apache License, Version 2.0 (ALv2).
https://aws.amazon.com/blogs/opensource/stepping-up-for-a-truly-open-source-elasticsearch/
https://aws.amazon.com/blogs/opensource/stepping-up-for-a-truly-open-source-elasticsearch/