I think Enscape should have a standing 1 year expiration date for all hosted content, unless the user specifically requests that it remain longer.
I also think there should be a setting to allow users to set their own expiration default. For us, our content changes so fast, we don't always want the panoramas to stay available in perpetuity.
Also, in the "Manage Uploads" dialog, you should have a way to delete any content older than "x" days.