Have downloaded, 2.5hrs, and installed, 1.5hrs, ACAD MEP 2012 for a free 30 day trial and have heard I can go beyond 30 days if I can locate the controlling file on my computer.
The question is, which file, where is it, and what do I do with it?

It sounds like you are looking to illegally extend the 30 day trial which is a violation of the End Users License Agreement.  Not going to get much help with that here.

How right you are and I do apologize for being out of line in this forum. Not a good start with something new.
I will try to contact AutoDesk and TSI for an extension but I am quite sure it will be difficult to even get a reply.
Been drawing pictures for near 40 years and the change from lead to 2D CAD was great. Now this past 10 year transition to 3D is outragious and I just want to learn all I can. Never used HVAC software till this assignment, it's all been 2D.
So, thanks for keeping me honest.
When I do visit again, it will be with a valid question.
Best Regards,
Joe

AutoDesk did have a program, at one time, where people who were out of work could download free versions of their software but I'm not sure it is still an option.  You might inquire.Another option is to look at AutoCAD clones like Briscad, DoubleCAD XT, ZWcad, progeCAD and alike.  They are very similar to AutoCAD and depending on the program either free or at a much lower cost than full AutoCAD and its vertical products.  They both read and write to the DWG file format as well.