Flows that are not associated with a subscription are free-tier flows that expire after a month. This looks like a gap in the documentation, and we'll work on getting additional details posted about this in the docs site.
If you (or your organization) have a Globus subscription, please open a ticket with sup...@globus.org
so that we can get you added to the Flows Users group which will ensure that your flows will be properly marked as having an associated subscription and avoid this limit in the future.
If not, you may delete that flow and deploy a new copy to create a new free-tier flow.
Globus Software Engineering Manager
Globus.org | University of Chicago