Hey Kazuki, thanks for the follow up inquiry! You can definitely use Claygent to find and validate the domains it finds for companies. Since it's a very simple task that won't require too much scraping, I'd recommend using your own API key for those types of queries.
When you're asking Claygent to scrape a lot more, as well as to output a lot of different answers then there could be a case for using either Clay credits or your own. Hope that helps!