The basic (non-premium) checks always work, we're not aware of a single case where the premium ad made the basic checks stop. Please post details on how to reproduce to either https://forum.languagetool.org/ or contact us directly at https://languagetool.org/legal/
Grammerly is one of my Top 5 must have extensions/tools. The Orange Monkey in an Ugly Human Costume, The USA's POTUS should have been given this 4 years ago. It would have saved him from some worldwide embarrassing tweets.