Well every solution will be just a workaround. As mentioned in older StackOverflow - question here and here there are two approach i would consider:
- You could create a log file or (encrypted) registry-key which contains a Date-checker and will increment the date as long it's everything legit (System Date is not older than "Last Run Time") and valid (License valid).
- You could read the windows log and search for time-changes and additional use the log for Date Check.
As you see: Both have still some flaws and with enough willpower can be overcome.