How does a migration to version 7.0 affect 3rd party app licensing?

[Nic Brough -Adaptavist-]

It doesn't really.  There are new APIs etc to deal with in the code, but the way the licences work is broadly unchanged.  The number of licences you need for an add-on remains as "it has to match the licence you hold for JIRA"

There is a slight complexity with the new applications though - if you've got JIRA + Software + Service Desk, you actually have three separate licences.  You don't simply add up the number of users though, your add-ons have to match the largest.  If, for example, you have 100 Software users and 50 JIRA Core users, then you have to deal with add-ons for the 100, not 150.