How do I add webroot to my PC? when I type in the keycode from my laptop it does not recognize the

I need help putting webroot on my home computer. .  I purchased webroot for my laptop and want to put it on my home computer.  I had a different webroot account on my home computer when I purchased it.  So, I only renewed my laptope account.  When I try to transfer the laptop key code to my home computer, it does not recognize the laptop key code. Keeps saying invalid code.  I know the code is good because I just renewed my webroot.  Thanks.