I use LinkMachine on one site, and I'd like to use it on a second site as well. How do I do this?

First install LinkMachine on your second site, using either the installation script or the online installer. When you run LinkMachine on your second site for the first time, do not create a new account; instead, log in using the same e-mail and password as you use on your first site. LinkMachine will then associate the two sites with the same account. If you have upgraded (or will upgrade) your account to LinkMachine Premium, that upgrade will be applied to both sites.