This question says that you can install the same purchase of Lion on multiple non-commercial Apple machines.
The accepted answer states the same applies to all App Store purchases.
My question however is, once you install something from the app store onto a 2nd machine, do you have to remain logged into the app store.
For example. My girlfriend just got given a mac with Snow Leopard. I want to log into the app store on her machine, install Lion, but then log out, and leave the app store logged into her Apple account.
Is that ok?