First off, this notice doesn’t affect your site in any way at all.
Anyway, there is a single line of code that theme authors can add to remove this notice from their themes. Just ask them to add it on the theme on their next update…
I wish I knew that code. I purchased a theme with Visual Composer that won’t update it saying “invalid license key”. So I also purchased the plugin itself and put the license key and now I find out it’s not working because it’s bundled. I feel like I’ve paid twice and still can’t update this software.
Updates can be important with database driven components for security.
I contacted the theme author they told me to buy it. So now I’m back where I started.