It took me awhile to discover but with a little trial and error, I discovered that the subscription expiry in Plesk can be found by going into the subscription itself. Once in the subscription, choose the “Customize” option and make sure that the date field at the bottom has the “unlimited” selection checked. Once that selection is checked, choose “update & lock” to save the setting.
This ensures that Website Projects (including this blog) which I host will not automatically suspend thus loosing new clients from the visit.