I recently purchased a 10 person license of Portfolio for our web team (4 people). My JIRA is licensed for 250 people. When I installed Portfolio for JIRA and licensed it, it tells me I must upgrade to a 250 person license order to use the add-on. Is it possible to use Portfolio for 10 people when we have a JIRA license for 250? It doesn't make much sense to pay $6600 when only 4 people need the add-on.
It is not possible to do that.
An add-on for an Atlassian application needs to be licensed to the same level the (highest tier) application is.
It makes perfect sense - you're using 4 people to manage 250. The 250 might not need some of the front-end functions of Portfolio, but the 4 are absolutely needing the information the 250 generate.