Unlike Photoshop, there is no activation, and yes, you can install on two machines with one licence without breaking the terms of the Adobe licence.
Yes, one Lightroom license entitles you to install the software on a maximum of two computers at the same time.
There is no activation mechanism in Lightroom (so no Help > Deactivate command). Compliance with the license is completely up to you.
Thank you very much both of you.
My situation is a little different and I am not too enthusiastic about what the answer is going to be...
I have a MacPro that has all my Lightroom data, and I want to use my MacBook Pro, which is newer and therefore on a newer Mac OS, to import and tweak before pulling those files into my main computer for more intense edits etc. My issue i think is going to be I have an older Mac with Lightroom 5 installed BEFORE the Adobe Cloud pissed off thousands of creative people, and the answer is going to be that I have to pay to upgrade.
I was forced into this because I failed to install LR on my Macbook sooner, so if you know how I can get the MBP licensed with my current key, then that would be great!
This question needs to be answered as I am on the trial version which has a couple of weeks left on it.
As it seems to me that you only two MacPros that you want to use now, there should be no problem in uninstalling it from the older Mac and installing it on the newest computer. As has been said before, there is no complicated activation like that with Photoshop, and Adobe relies on an honour system with Lr, trusting that you will uninstall it from your old computer before putting it on a new one, keeping your total of installs to a maximum of two at any one time.
OK but right now the older Mac Pro is my production working machine that has already been licensed the old fashioned way with a key they sent to me last year. And when the trial period runs out on the newer computer (a Mac BOOK Pro) it will cease to work!
Just to be clear, is the installation on the newer MacBook Pro a standalone version, like that on the Mac? If it is, you can make it into a full version by using the serial number you were sent last year. However, if you have installed the Creative Cloud version on the newer machine,then the old standalone key will not work and and you would have to buy a subscription from Adobe.
I forgot to ask as well whether you are using Lr v5.