Once you've purchased Social Link Pages Pro, click on the "View details and downloads" link on your "purchase history" page:
Then click the "download Social Link Pages Pro" in the "products" section:
This will download the pro plugin to your computer.
Once downloaded, find the zip file in your downloads folder.
Sign into your WordPress site, go to "add new plugin" and upload the zip.
Note: do not remove the free Social Link Pages plugin.
Activate the uploaded plugin, and you're ready to rock!
Adding your license and registering your site
To get your license, click on "view licenses" on your "purchase history" page on the https://sociallinkpages.com website.
Click the key icon next to the product name, and your license will show:
Copy your license.
Sign into your WordPress website. After installing the Social Link Pages pro plugin, there is a new "Pro settings" page under the "Link pages" menu in your WordPress admin:
Visit this menu page, and you'll be asked to enter your license:
Paste in the license key you copied, and your site will be registered!