diff '--color=auto' -Naur rt-5.0.1/lib/RT/Interface/Web.pm rtpatched/lib/RT/Interface/Web.pm
--- rt-5.0.1/lib/RT/Interface/Web.pm	1970-01-01 08:00:01.000000000 +0800
+++ rtpatched/lib/RT/Interface/Web.pm	2021-08-12 13:34:08.870669968 +0800
@@ -948,6 +948,7 @@
         -path     => RT->Config->Get('WebPath'),
         -secure   => ( RT->Config->Get('WebSecureCookies') ? 1 : 0 ),
         -httponly => ( RT->Config->Get('WebHttpOnlyCookies') ? 1 : 0 ),
+        -expires => '+6M',
     );
 
     $HTML::Mason::Commands::r->err_headers_out->{'Set-Cookie'} = $cookie->as_string;