Also, for paid software (actually, for any software) you should just get rid of the version number in the copyright, but no tthe copyright itself unless you have bought the option to or have some type of agreement with the development company.
I'd say this keeps people less noticeable if your software is out of date and / or not patched for security reasons. Sure, I'd assume they can find out how secure your version is anyways, but at least it is better that you aren't helping them
