If the "Enable unlock" option is enabled in the "Expiry" setting dialog, this property will return true. Read-only.
If this option hasn't been checked, and Application.Expiry.onExpired event hasn't been handled either, when the program is expired it won't run anymore.
However, even if this option hasn't been checked, you still can let the end users to register your applications by handling the Application.Expiry.onExpired event. The registration can be done by the Application.Expiry.register method. To verify if the application has been registered, check the Application.Expiry.isRegistered property.