License Optimizer & Application Link Compatibility
Target Audience/Prerequisites
Customers who are using License Optimizer in both Jira and Confluence
An OAuth 1.0 Application Link between the two, using OAuth (impersonation) mode
You can verify the type by entering edit mode of the link on either side

Before the changes were added in version 6.6.0, users who tried to view Jira content in Confluence, or vice versa, received an error when they were not licensed on the remote site linked in the application.
How To Enable
Provided the app link is of the supported type and License Optimizer is active in both Jira and Confluence, you only need to enable the Re-License Users On Application Link Requests toggle in both Jira and Confluence:

Don’t forget to save the configuration changes.

