Expiring EAPs

I was forced to install 6.1 to resolve an intellisense problem that made your product unusable to me.  That build was Nov 15 and it's been working fine since.

Today it apparently expired and I'm having to waste time uninstalling a working product and then going through the install process with a new build that may or may not work.

Why do these builds expire?  I'd rather not play this game every 3 weeks until you decide to release 6.1.  I just want to do my job.