Need help!!!

Hey, im starting darkrp server and were looking to buy addons soon from gmod store! the question ia im looking for advice! that me and my mate starting running darkrp server and im the owner and hes co-owner! any chance he can buy addons for himself and use them on my server as hes co-owners because incase the future he creates server and needs the addons!

Can have some help please thank you!