title: In what OS folder should I create a hidden file to denote that my client's license has expired?
body: <p>I understand this is not 100% safe but it is at least something. After my software license expires I would like to write a hidden file <strong>somewhere</strong> that my software can later check to see if the license has expired. That way, even if the client re-installs the software it won't work because the file will be there. What location/folder do you suggest that I do that for Linux, Unix, Windows and Mac? Any other simple ideas will be also appreciated.</p>