Our practice has been to not activate our Windows 2008 templates.
Up until now this hasn't been a problem but based on the KB below it appears this could possibly become an issue over time.
http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=201414...
What is the best practice, to activate templates?
I'm also confused with what causes the Rearm program to run.
Always keep the VMs licensed correctly, even if you're turning them into templates. And as stated in the KB you posted; volume licensing is the smoothest way to go.