You do not need to deactivate WinCatalog on your old computer, but if you want to do this, you may just uninstall it.
To move WinCatalog to you new computer please perform the following steps.
1. Download and install the latest version of the trial edition of WinCatalog to your new computer and activate it using your registration key. You can download WinCatalog here: http://www.wincatalog.com/thankyou.html
2. Copy or move your existing catalog file from your old computer to the new one. If you do not know where your catalog file (or files) is located, please run WinCatalog on your old computer, this will open most recently used catalog file. Click the Catalog button (left from the Main tab of the Ribbon toolbar) and in the Catalog section you will see the full path to the currently opened catalog file. In the Recent section, you will see recently used catalog files (if any).
The Catalog button:
If you double click on the catalog name or file path (on top of the Catalog section), this will open the containing folder in Windows Explorer.
3. That's it. After moving your catalog files to the new computer just run WinCatalog on the new computer and open these files (Catalog -> Open Existing).