Neither, actually. My response to you is, I think, the first post I ever made in response to a question. But I enjoy being helpful. I'm not nearly cool enough to be a dev or an admin.
If it were me, personally, I'd abandon Virtuemart. It's a great product, but I think unnecessary for what you're trying to do.
I'm still trying to grasp the whole "how do I know" thing. Whether they run indefinitely, yes. You set it up so the software knows when it expires, when to notify them, when to know to cancel, et cetera. The only thing I'm not totally sure about is that it sends you notification.
I think what would need to happen is that the customer would need to change the subscription type. If the entire purpose would be just to order cheese, I don't think a monthly subscription would be the best way to go. I think this would depend on other features of the site. If it's JUST the cheese, I don't think there'd need to be a subscription at all.
Let's take your example. The software is going to tell them their subscription is going to expire. You can set it up so it tells them that it's going to expire and they need to pick another cheese or keep the same one, but they need to pick a cheese regardless. It'll notify you, I think, that they placed another subscription order. (If not, it should.) You can ship out the right stuff.
I think this entire thing depends on what other benefits you offer. If you don't offer a "How can you use cheese rind" discussion, I think you'd just set it up as a standard merchandise purchase. If you have forums, newsletters, whatever... You'd just set up as a subscription thing.
One of the things that I like about this software is the flexibility. There are a lot of things you can do with it. I'd be happy to discuss this in more detail if I'm still not getting my point across... Which I don't think I am. But I don't think you need Virtuemart. I think CBSubs is all you need.