Redirect EDD license renew request to Freemius

sp-edd-fs.php

<?php

add_action('add_meta_boxes', function(){
	add_meta_box('sp_edd_fs_metabox', 'Freemius data', 'sp_edd_fs_metabox', 'download', 'side', 'default' );
});

function sp_edd_fs_metabox( $post ){

	$plugin_id	= get_post_meta( $post->ID, '_sp_edd_fs_plugin_id', true );
	$coupon	= get_post_meta( $post->ID, '_sp_edd_fs_coupon', true );

	echo '<p><label for="_sp_edd_fs_plugin_id">Plugin ID</label><input id="_sp_edd_fs_plugin_id" type="number" value="' . esc_attr( $plugin_id ) . '" name="_sp_edd_fs_plugin_id"></p>';

	echo '<p><label for="_sp_edd_fs_coupon">Coupon</label><input id="_sp_edd_fs_coupon" type="text" value="' . esc_attr( $coupon ) . '" name="_sp_edd_fs_coupon"></p>';
	echo '<p class="description">Set a coupon if you want to give users a discount</p>';
}

add_filter( 'edd_metabox_fields_save', function($fields){
	$fields[] = '_sp_edd_fs_plugin_id';
	$fields[] = '_sp_edd_fs_coupon';
	return $fields;
});

add_action( 'template_redirect', function(){
	if( ! function_exists( 'edd_is_checkout' ) || ! function_exists( 'edd_software_licensing' ) ||  ! edd_is_checkout() ){
		return;
	}
	$license_key = isset( $_GET['edd_license_key'] ) ? $_GET['edd_license_key'] : '';
	$download_id = edd_software_licensing()->get_download_id_by_license( $license_key );
	if( ! $download_id ){
		return;
	}
	$plugin_id	= get_post_meta( $download_id, '_sp_edd_fs_plugin_id', true );
	$coupon	= get_post_meta( $download_id, '_sp_edd_fs_coupon', true );
	if( !$plugin_id ){
		return;
	}
	$args = [
		'license_key' => substr( $license_key, 0, 32 ),
	];
	if( $coupon ){
		$args['coupon'] = $coupon;
	}
	$url = add_query_arg( $args, "https://checkout.freemius.com/mode/dialog/plugin/{$plugin_id}" );
	wp_redirect( $url );
	exit;
});