Complimentary ML Update

[Feed Me]

So I'll be getting a free upgrade to Mountain Lion with my new MacBook Pro when it comes out.

We also have an iMac in the house, which will be upgdraded to ML as well.
Can I use the same "purchase" of ML on the iMac as well as the MacBook, or will I have to pay for the iMac's upgrade?

I know that ML software updates now go through the AppStore rather than through Software Update, but are they tethered to an Apple ID like other AppStore updates? Or can they just be downloaded without having to log in?
I ask this because the iMac will be signed into a different Apple ID than the MacBook.

Also: for anyone who got a complimentary upgrade to Lion last year, how was it delivered? AppStore? Website download?

 

[comdex]

You can install ML on the iMac as long as the Apple ID that you got ML in first place is logged in the iMac. I think after that you can change it to another apple id