Originally Posted by Cyber Fucker

It's a very bad idea to host with a sponsor and even worse idea to use domain name of sponsor. It leaves you out of the control of your traffic. But let's go into specifics of subdomain use as that was the question. So for example if sponsor decide to cut you out or close affiliate program then you lose all your work you put to promote it. If you use your own name you can always switch to other sponsor and keep the traffic (money).