Saving courses from Rise for later use

As you noted, if an account holder stop their subscription/license, they will lose the content they have in Rise, as well as in Review. Any links to that content won't work after the license expires.

Articulate will maintain the content up to 6 months after a license expires. If a license is reactivated within that timeframe, the account holder will be able to access the content again. 

If your client wants to stop their license for >6months yet still be able to edit existing Rise courses in the future, they need to send a copy of each Rise course to someone else with an Articulate license—and trust that that person will keep their license active, will not edit/delete the courses, and will transfer them back when the time comes. (And hope that nothing bad happens to that person...)

I'd also recommend that they save all of the assets related to the courses. That will make it easier for them to re-do the courses, if needed.