Hello Laurens!
A PRO or Enterprise subscriber is entitled to download and use the Kibana plugin in as many servers/clusters/deployment they want, as long as the hardware belongs or is rented by the Licensee.
The problem arises when a PRO/Enterprise Licensee wants to use our technology to provide an on-premises solution to their customers.
If you only sell professional services of installing ReadonlyREST Enterprise/PRO, your customers should buy a license from us.
If you redistribute derivative work that includes any of our technology, need to acquire an Embedded license.
Because our Kibana plugins rely on our (GPLv3 licensed) Elasticsearch plugin, redistributing derivative work under a non-GPLv3 compatible solution would put the Licensee in breach of the GPLv3 itself.
In order for you to side-step the above limitations, as we own the 100% of the intellectual property on the code, we are able and willing to distribute our Elasticsearch plugin to “ReadonlyREST Embedded” Licensees a fully commercial license, so redistributing non-free products to third parties will be legally possible.
Our Embedded license does not set any limit to how many times you can sell the derivative work.
If you have any further specific questions, please feel free to contact us via email (support AT readonlyrest.com)