There are 2 options to do:
1. Use the form field to edit and configure the expire time to set the timer validation of whatever the value we need for expiraton for the self registration user requiring sponsor approval.
2. Use the guest mac caching to set or cache the timer from when the user authenticated maintain the authenticated role for "X" number of time.
I see the option 1 is easy compared to option 2.
Thank you
Sriram