See the description on the options tab -> registration:

"Please enter your purchase code here to finish the registration and unlock all features of advanced iframe pro. Your license key (purchase code) is located inside your digital purchase receipt on your CodeCanyon Downloads page. To retrieve your license key, visit CodeCanyon.net/downloads and click "Download > License Certificate". Please note that your purchase code will be validated and logged together with relevant data to detect fraud. Also see the privacy policy here: https://www.tinywebgallery.com/blog/privacy-policy for details. Please do not share your purchase code as it will be blocked when misuse will be detected."

Best regards,

Michael