OK! I installed the trial version already in the testing version and used it during the 15 days and then bought the license. It’s working perfectly, with no bug so far! (Debian 10 + Gnome 3.26). I update every day and it has not stopped working any day!
I just got this message when updating the packages by apt … when I installed .deb I believe that the default repository added was the version of my system, in the case of testing (buster). @jimperio Do you advise changing from buster to stretch in this case? Or should I wait for the release of the testng repository for you?