You must understand that if you upgrade to QB Enterprise 2015 you agree to Intuit’s new yearly subscription pricing model. You are obligated to pay the yearly renewal fee. If you don’t and your subscription expires the software will “conk”.
If you are on QB Enterprise 2014 or earlier versions you can continue to use that version of the software without upgrading and the software won’t “conk”.
However if you use payroll and QB Enterprise periodically, about every year or two, Intuit will discontinue support for payroll in order versions. So sometime in 2015 or 2016 Intuit will most likely discontinue support for the 2014 version.
I tell you all this in the interest of full disclosure.