Can I install Mountain Lion on wife's MBP w/my iTunes acct.?

So I have a problem that may not be uncommon for a household with multiple Macs/iOS. My wife and I have our own Apple IDs mine on my iPad/iPhone and iMac and hers on her MBP and iPhone.

My problem is I want to know if I can sign into the App Store on her MBP, download Mountain Lion which I've bought (and already installed) on my iMac and install it on her computer without issues. By issues I mean after its installed she signs back into her Apple ID, will the OS still run? Do I have to remain the admin and have her Apple ID added as a user?

What is my best course of action to get ML on her MBP without repurchasing it?

P.S. I know you can make a bootable drive but I've already installed it on my iMac so it may be too late for that unless there is a work-around.

Any suggestions?