You can view and download previous versions of all of the 3D WebView packages through the Vuplex Developer Dashboard. If you purchased 3D WebView through the Vuplex Store, you can log in with the account you used to make the purchase. If you purchased 3D WebView through the Unity Asset Store, you can access previous versions by following these steps:
Create an account by going to https://dashboard.vuplex.com and clicking the "Sign up" link in the top right corner.
Once you are logged into the dashboard, click the "Add products" link, enter the invoice number from your Asset Store receipt email, and click "Redeem".
Once you see the 3D WebView packages in your dashboard, you can click the "See all releases" link for a package to view and download its previous versions.