If you can log in, you're a member. But you may be set to "not currently available", in which case your name won't show in most searches.
If you find that you can't log in, try getting a password reset email sent to your address. Just visit the password reset page and enter your email.
We do delete members annually if they haven't logged in for more than a year, and we delete members when they are consistently unreachable. In both of these cases we attempt to contact you first.
If you account has been deleted, you are welcome to create a new one at any time.