I expect it to be done one of 2 ways. Either you will get a redemption code for the Mac App Store (like the codes on iTunes gift cards or Starbucks App of the week), or you will have to install a validation .pkg file (like they do with the Apple Seed program).
Either way, the software will be available via the Mac App Store (updates tab) and/or Software Updates. And you have to have already registered for the program to get "in", however they do it.