Do i have to flush the session or the session variables after the page is submitted?

I have a Laravel app that uses sessions for persisting data between requests(Which is a three page app).After the user has successfully submitted the page or gets to the confirmation page.Is it advisable to flush the session as those session data is not needed or is there any alternative way to handle it?? Is there is any disadvantages if we do not flush the session data??

via Chebli Mohamed