itunes - subscription question

I click "subscribe" and it downloads a podcast. If I look at this podcast in the "podcasts" area, I see a button which says "Unsubscribe" in the bottom left. I put this podcast on my ipod, then delete it off my computer. When a new episode of this podcast comes out, I don't get it.

So I am hypothesizing that I need to keep at least one episode of a podcast in iTunes in order to remain subscribed to it.

Is that correct?

If so, it seems annoying. Is there any way around it?

No one can even tell me if the theory that I have to keep an episode in itunes to remain subscribed is correct?