Forced Ads

Hello,

Is there any how-to or anything which instructs me how I can force users of a specific package to show ads?

I am willing to pay for this. I have already made my own billing system but I want to offer free hosting as well. I want to show an advertisement on though.

I would appreciate some help.

Check mod_layout for apache (search google)

I know this is an old topic but still if anybody else has this question