If you are getting a Signature Invalid For Licence error when trying to enter your licence details, this means one of two things:
Your subscription has expired and you will need to renew your licence to continue using the program as normal; or,
Occasionally, we have to get everyone to update beyond a particular version of the program. We do this by making the Online Licence Install box pop up upon opening the program, requesting you enter your registered email and subscription ID; when these details are entered, you will get a Signature Invalid For Licence Error. At this point, if you know your licence is not expired, you should click Cancel to the Online Licence Install and then click on the Check For Updates Now button in green writing on the bottom toolbar of Lightning Payroll. Once updated to the latest version, the program will ask for your licence details once more, at which point you can enter them again, and they will be accepted.