How to prevent method invoking when Attribute return false? [duplicate]

I have a software that requires a license key validation on some methods. It a little bit uncomfortable to write a general wrapper for this purpose, so I want to write something like this:

    [EnsureThat(LicenseKeyAdded = true)]
    public static void SomeSeriousMethod()
    {
       // My very confidential code
    }

LicenseKeyAdded is a property inside the class, that was set somewhere outside. And the main idea is not to execute this method when the attribute's result is false (display alert message instead)