I am away from my home computer and I installed Lightroom 5.6 on my laptop since I need it now and when I go to use my S/N I got when I bought Lightroom 5 it says its invalid. Is it because I have it installed on my main computer? I had this problem before when I had to re install but forget what I did to fix it. Any ideas?
LR can be installed on up to two computers.
Perhaps you’ve installed the CC version of LR and need to install the standalone version?
Uninstall the LR you have installed, then install the LR 5.6 update from here: