Sorry, but if you want a license for that program, you have to buy it yourself. DonationCoder only offers free licenses for the software it produces, and sometimes they also offer a few ones for external software if there's a giveaway. Such giveaways are previously discussed with the authors of the software that's being offered.
The site also offers discounts for some software (again, in accordance with their authors), but ConvertXtoDVD is not one of them. Although I think it has been featured in one way or another on the site.