STEP 1: Login to ThemeForest.
STEP 2: Go to Downloads page.
STEP 3: Click Download button next to ListingPro, and select License certificate & purchase code.
STEP 4: Open the license.txt or license.pdf file and copy the Item Purchase Code.
STEP 5: Go to ListingPro CC > License
STEP 6: Insert the Item Purchase Key, and select Instance Mode
STEP 7: Click Activate
NOTE: If you need to migrate your site from one site to another make sure to first deactivate the license on the current site and then activate it on the new site.