It's
best solved on your server. Conditionally include the links
based on member/non-member.
If
you can't do that, you could remove the links with Javascript,
if there's some way for the script to know if the user is
logged-in or not. Realize, though, that this does not secure
your links. You need to have the server refuse to serve those
documents unless logged-in
And, so, it is only a cosmetic
solution to avoid confusing non-members with links that will not
work for them.
There is a minor security concern
with this, even if your server refuses to serve the documents. You
are exposing the URLs, which in some circumstances might
be considered sensitive, and, as well, represent
additional known points of attack.