Copying Siemens licence floppy disks and whether it is legal or not has been covered a few times in the past on this forum.
As ninanderson wants to copy the floppy for his 'own use during the project', I would guess that in this case it is not legal, as pointed out by OZEE, I state this because it is not his disk to make a back up of, I suspect that when the project is finished he will still have Step 7 on his PC/laptop and will also have a copy of another persons licence on floppy to run the software.
ninanderson,
What version of step 7 have you been lent? The later versions will run quite happily without the authorisation, you just get a 'nag screen' everytime you try to do something, the nag screen tells you that you do not have a valid licence for the software, I am sure that v5.3 and later, or those that use the floating licence, need to have been authorised before this facility is available. As you will have installed the licence lent to you by your client then this should not be a problem. As to the legality of doing this, I don't know about that. It is certainly unethical.
I am sure other S7 users will have their own views on this
Paul