Vynir
If you mean skills (or skill bricks), they remain in your account indefinitely. You can remove them from your toolbars, but they remain accessible, and you can reuse them in new stanzas...
that's something that took me a long time to understand. So for a while, I didn't dare remove them from my toolbar, for fear of having to buy them again. I don't know if there are better explanations now for beginners. But in 2011, it wasn't clear.