Which version of Lightroom do you currently own?
What do you mean by LR Account. LR can be installed on 2 separate computers at the same time.
Also If you are going to retire the first computer you had it installed on then you need to Deactivate that first computer by Signing Out of LR then Uninstall it.
You can then install it on the other computer without using up the allotted number of installs.
I have version 5
As Shootistbond said, You should be able to able to run Lightroom on maximum two computers at a time.If this is a third attempt Simply uninstall Lightroom 5 from one of those two Computers and install it on new computer.
Download link for Lightroom:- Install Photoshop Lightroom
thanks for the information. I already installed it on one computer, but now i am going to buy a new one. But on the site of Adobe I can't find the option to re install for a second time (I have to buy it...). What can I do please?
Use the Link in Akash's post do Download LR 5.7.1 and do NOT Delete that download after you install it on the second computer.