backing up or migrating iWork w/out the disc or ser #?

[Psurfer]

iWork '08 exists on a mac I purchased, purchased via download by the previous owner, who kept no backup disc or record of the serial #. I he had, he'd give that to me. Will Apple have the ser # info if he calls in and requests it?

In the meantime, would it work to migrate the program from one mac to a 2nd (while clean installing Leopard on the inital mac), then migrating it back to the 1st machine, via Migration Asst or FW T-mode?