McAfee Antivirus Plus 2011?

I bought this product online. It worked for my laptop, but when I try to install it in the other laptop it won't work. It says that the product key won't work. So I install McAfee again, but this time, the internet connection wasn't working. I have until June 30th to activate, but I'm really really sad because this laptop isn't very good anyways. Why won't the product key activate, even though this product says 3-users. (it is 3-users because it says so)