You can log into your own account and all, but I think her machine will then count towards one of your 5 authorized machines that use/see your content and apps. It's not a big deal if you don't expect to need 5 different machines to need access to your purchased stuff, but just to be sure you can deauthorize the computer from your account when you leave (go to store> deauthorize this computer).
It's not a big deal as even if you forget then reach your limit later, you can deauthorize ALL devices that currently are authorized then just add the devices you actually use.