This filter allows you to add certain arguments to the premium URLs in the free theme Dashboard.

For example, you can add your affiliate ID and campaign to all URLs in the Dashboard and Customizer that point to GeneratePress.

So if my affiliate ID is 1, and my campaign name (optional) is test, I would do this:

add_filter( 'generate_premium_url_args', 'tu_affiliate_id' );
function tu_affiliate_id( $args )
	$args = array(
		'ref' => 1,
		'campaign' => 'test'
	return $args;

Now all of the URLs pointing to in the Dashboard will have my affiliate ID and campaign added to them.