Moodle 2.6+ (Build: 20131122).
It is not handled by the Cron so why does the renewal of the keys fail? I can't find any reports of this as a problem since back in 2008.
Thanks for any help and insight that can get me out of having to manually renew the keys every 28 days.
According to config-dist.php you must add in your config.ph this:
$CFG->mnetkeylifetime = 28;
So you change that to 365 o whatever you like
After that, you must delete and update any existing key.