I have a few products I want to promote. My question is should I have a seperate domain for each product or can I use a hub page? example: www.hubpage/product1 www.hubpage/product2 www.hubpage/product3
Depends on type of products and how inter-related they're. One website will work most of times as you can focus all your efforts to a single point.
I don't think it's really possible to answer this question effectively without knowing what kind of products they are and what kind of branding they need. If they are information or software related and have different titles, then you would definitely want different domains. But if they are related in terms of branding and category, then you should have no need to have separate domains.