Some EULAs state that a user may install the software on a desktop AND a portable machine (notebook) that is to be exclusively used by the same one user. The reason the two prior activations (dad and friend) work is because it used up the two activations per license.
It's still breach of license to install it on two machines for two or more people -- but this is the technical reason why the two prior activations are probably still working.
Adobe CS4 Design Premium Suite is like this and it's likely Office is too-- copy-and-paste from Office 2007 EULA:
a. Licensed Device. You may install and use one copy of the
software on the licensed device.
b. Portable Device. You may install another copy on a portable
device for use by the single primary
user of the licensed device.
Bottom line: YOU may install it on one desktop, and one notebook just for you.