If you don't have a license, the files are locked after some time. This is to remember that using Stackz without license is only permitted for the trial phase, not for a longer time. (Nevertheless, you can unlock the files even without license - but it will reset the learning statistics in your file...) So if you have a license, simply enter the license code and they will become unlocked.
The mail issue is probably not related to Stackz, but to your operating system and its settings...
The mail issue is probably not related to Stackz, but to your operating system and its settings...


