After purchasing the product, you will receive a serial number string. To unlock the product and remove the evaluation message from the generated PDF documents and images, you need to set the static LicensingSerialNumber property in your application.
Set the serial number globally using the LicensingSerialNumber static property.
// Replace the demo serial number with the serial number received upon purchase
// to run the converter in licensed mode
Licensing.SerialNumber = "YCgJMTAE-BiwJAhIB-EhlWTlBA-UEBRQFBA-U1FOUVJO-WVlZWQ==";