DeepL Pro is available for character based GT4T license owners with no additional charge. And you don’t have to pay DeepL for that.
Here is the proof that GT4T is using real DeepL Pro:
1. When you press ctrl+win+j for DeepL alternative translations, only one item is returned. (DeepL Pro doesn’t support alternative translation yet)
2. See this screenshot of GT4T DeepL Pro usage for this month.