I am unable to find where to start a new question??
So I'm asking a new question here: How do I register the LRT on my second computer. With a very quick search, I cannot find the answer although I am sure you have answered many time.

There is a "Post thread" button on the top right in the forum view.
Short answer to your question: just install LRT on the second machine and activate the license key, that you've received via email there.