No, I don't think DDLKit Pro is authorized by Microsoft. Typically, these applications have a Microsoft logo embedded into their website, but this one lacks that. However, even if it had such a logo, you wouldn't know exactly if Microsoft supported them or not. Most likely, that's a marketing scam to encourage sales.
It's up to you to decide if the app is good or not, but here is the link to the website: http://www.dllkit.com/en/