You can use the SetUser XML API message (meetingTypes >> meetingType), allowing the normal PRO session type and disabling the custom (restricted) session type and vice versa.

Is this a classic Webex Meeting Center site or a Teams integrated site? If it is Teams integrated, i.e. you can manage it from the Control Hub as opposed to the Site Admin pages, please drop me a personal message, I may know a possible workaround for...

There is a good Python tool for that, published at https://github.com/DJF3/Webex-Message-space-archiver 

Webex Centers meetings are restricted by default to a maximum length of 24 hours. Technically it is possible to set a site for a longer period, but I am not sure if they will do that for you. Try it by submitting a case and see the result.

Sorry, my bad. This link will help you I hope: https://www.cisco.com/go/hybrid-services-directory