Office 2008 did not use activation. As long as you remove you can re-use your keys.
Office 2008
Standard/Business version has 1 CD key
Home & Student has 3 CD keys
Each Product Key represents a separate license to use Office 2008.
Each license entitles you to install on 1 "desktop" + 1 "portable" Mac. The restriction is that you are not permitted to use any of the Office programs on more than 1 of the 2 systems at the same time. If both Macs are on the same network you will be physically prevented from launching an Office program on the second Mac if any Office program is running on the other.
In total, the 3 licenses (Product Keys) for Home & Student enables you to install on 6 separate Macs... Theoretically that means 2 Macs for each of 3 users or individuals.