Was the Anti Theft included as a package deal with 360? ie, do you use the same product key to activate both products. If so that is why the license issue.
You have installed on the desktop and laptop. That is 2 devices. Then you installed on your smartphone. That is the 3rd device. The iPad is a 4th device, and it seems you do not have enough licenses for that.
If this is not the case, then you might be best to contact Support via online chat and ask them for help with your issue. www.norton.com/chat
Please let us know what they say.