Case 1) The official solution is to delete the old installation and install it on the “new” PC form the LOGO!Soft Comfort DVD.

If you buy is once, you are only allowed to install it once.

Hint:

As the DVD is not copy protected, you can install from any copy too, e.g. from an USB stick.

Case 2) If you want to update it (and your old installation is on another PC as in your case), you can show the setup the DVD as license.

And you have to delete the old installation, if you have only one license.

Case 3) If you don’t have the original DVD and no copy, you have to buy a new DVD. Then it’ a new installation, see case 1.