Atlassian has posted the following relevant information regarding Atlassian Marketplace addons and development licenses of JIRA:

Which points to:

Go to the section titled, "Can customers use developer licenses for my add-on?" which has instructions on how to get a developer license for add-ons.

In summary: A
developer license can be generated (free of charge) once the plugin has been purchased and can only be installed on a development licensed version of JIRA.