You can display your own license dialog boxes instead of using Thinstall's built-in dialogs.
To do this:
1. Ensure that Display register dialog on start and Display register dialog on quit are disabled using the License Settings project setting. This tells Thinstall not to display any dialog boxes when your program starts or quits. It also allows your program to run even if the current license has expired.
2. When your program starts it should check the Environment Variables set by Thinstall to determine if the current license has expired. The easiest variable to check is TS_EXPIRED
3. If the current license has expired, prompt the user to enter a new key. Optionally, you may want to allow the user to enter new keys even if the current key has not expired.
4. To set a new "current license key", simply call the Windows API command SetEnvironmentVariable("TS_CURRENT_KEY", "new_key_value") For details on SetEnvironmentVariable return codes, see this page.