Static content is things like unlocking more functionality within an app, that doesn't change over time.
Very basic example: Let's say I have an app that displays the workload on the CPU as a percentage in the macOS menu bar. I might want to give the user an option to pay to unlock features that also displays the workload percentage for the GPU and RAM in the macOS menu bar.
For this, automatically renewing subscription is not allowed. But would a non-renewing subscription be acceptable, or does it have to be a perpetual (pay one time own forever) in-app purchase for static content?