I am going to take a guess that you will not get credit, but not because of the reasons you are expressing. My understanding of the system is that you will need a multitude of gamers downloading and using your livery in order to receive any credits in the first place. If I am correct, one download from your friend and that friend being the only one racing with it will do you no good.
yep, both the previous replies are correct. 1 person using it(unless they drove a ridiculous amount with that paint) isnt enough to get paid, and unsharing it does remove your ability to get paid.