I'm trying to learn as much as I can about ESXI, without having to worry about license limits or restrictions, but I don't want my VMs to drop dead either. I found this page that describes how you can reset the evaluation mode with minimal server interruption.
Create a Shell Script at /usr/local/bin and make it executable
vi /usr/local/bin/resetesxi.sh
Include the following:
rm -r /etc/vmware/license.cfg cp /etc/vmware/.#license.cfg /etc/vmware/license.cfg /etc/init.d/vpxa restart
Do a chgmod to make it executable
chmod /usr/local/bin/resetesxi.sh
Add it to cron:
vi /var/spool/cron/crontabs/root
And add the following: