Restricted access to EZ page based on product purchased

I sell a software product which now requires a patch, but I want to make sure that only existing owners of the product can download the patch. (It's a big patch, and I don't want those with pirated copies using my bandwidth.)

I know there are a lot of ways I could do this, ranging from replacing the original downland and reactivating it for all customers, to emailing a link to existing customers. However ideally I'd like to create a members-only type page for those who have purchased this particular product. This would allow for some ongoing updates, related downloads and special offers.

So I'm looking for a way to allow access to a specific EZ page based on a ownership of a specific product.

Or any other ideas to do this simply.

One thing I've been thinking about is creating a 'Group Name' such as 'VIP', but rather than use it for a group discount, it would allow access to a VIP area.

I'd probably assign the new customer to the group manually.

In which case I'd just need to check for the group membership. Seems like something I could figure out, if I put my mind to it.

Any suggestions most welcome though.

Two things involved:
a) the logic to determine eligibility ... and group-membership is a good choice
b) putting that logic into the two relevant places:

• i) places where you want the links to that page to appear
• ii) the page itself to prevent unauthorized access

Thanks for that, I've just about decided on this:

A 'VIP' sidebox, visible to everyone; linked to a page which will check if visitor is a member (logged in, group member); if not it'll explain what you are missing out on, otherwise it'll include the VIP links etc.

Seems simple enough, absolutely no experience with this sort of thing, but looking forward to getting it to work