AC3 encoder question?

Sorry, couldn't decide which Forum to post this question? My trial Dolby encoder in Premiere after the next few Renderings. And I haven't puchased the TMPGenc AC3 plug-in, yet. And wasn't looking forward to paying the $300-$1000 price tag on the Surcode Dolby Plug-in for Premiere. Now, FYI i have the TMPGEn DVD Authoring program as well as Sony Vegas...it had Mainconcept AC3 encoder with it, right? and the TMPGEn has the TMPGenc AC3 plug-in, right? And Nero has AC3 encoder with it? So, how do I/ why can't I use any of these with any of my other Editing/Authoring programs? What do i need to do to pull these encoders out of these "discarded" authoring programs to use with the "better/upgraded" tools I have on my computer like DVD-LaB Pro<<it only wants to recognize the TMPGenc AC3 plug-in, none other.