Adding Own Template Library

You can also add your own beautiful Template Library both blocks and templates. When you design your beautiful templates, export it, you will get JSON file, which can be added on your own theme as template library.
Here is example code

/**
 * Add Own Templates
 *
 * @param array $templates_list
 * List of the Templates
 *
 * @return array
 */
function prefix_add_own_templates( $templates_list ) {

    $my_templates_list = array(
        'unique_prefix_id_1' => array(
            'title' => __( 'Title of Block', 'text-domain' ),/*Title*/
            'type' => 'block',/*either template or block*/
            'author' => __( 'Author', 'text-domain' ),/*Author Name*/
            'keywords' => array( 'about-block', 'about 3' ),/*Search keyword*/
            'categories' => array( 'about' ),/*Categories*/
            'template_url' => 'https://www.domain.com/gutentor-block-or-template.json',/*Json file url */
            'screenshot_url' => 'https://www.domain.com/gutentor-block-or-template.jpg',/*Screenshot of block*/
            'demo_url' => 'https://www.demo-domain.com/',/*Demo Url*/
        ),
        'unique_prefix_id_2' => array(
            'title' => __( 'Title of Block', 'text-domain' ),/*Title*/
            'type' => 'template',/*either template or block*/
            'author' => __( 'Author', 'text-domain' ),/*Author Name*/
            'keywords' => array( 'about-block', 'about 3' ),/*Search keyword*/
            'categories' => array( 'about' ),/*Categories*/
            'template_url' => 'https://www.domain.com/gutentor-block-or-template.json',/*Json file url */
            'screenshot_url' => 'https://www.domain.com/gutentor-block-or-template.jpg',/*Screenshot of block*/
            'demo_url' => 'https://www.demo-domain.com/',/*Demo Url*/
        ),
    );
    return array_merge( $my_templates_list, $templates_list );
}
add_action('gutentor_advanced_import_templates','prefix_add_own_templates');

Gutentor now supports premium blocks and templates

On the free version of your plugin/themes add your pro block and template using the following code.
It will show premium blocks and template on the free version of your plugin/themes but does not allow it to import.

/**
 * Add Premium Templates
 *
 * @param array $templates_list
 * List of the Templates
 *
 * @return array
 */
function prefix_add_own_premium_templates( $templates_list ) {

    $my_templates_list = array(
        'unique_prefix_pro_id_3' => array(
            'title' => __( 'Title of Block', 'text-domain' ),/*Title*/
            'is_pro' => true,/*is_pro true or false*/
            'pro_url' => 'https://www.domain.com/pricing',/*pro url*/
            'type' => 'block',/*either template or block*/
            'author' => __( 'Author', 'text-domain' ),/*Author Name*/
            'keywords' => array( 'about-block', 'about 3' ),/*Search keyword*/
            'categories' => array( 'about' ),/*Categories*/
            'template_url' => 'https://www.domain.com/gutentor-block-or-template.json',/*Json file url */
            'screenshot_url' => 'https://www.domain.com/gutentor-block-or-template.jpg',/*Screenshot of block*/
            'demo_url' => 'https://www.demo-domain.com/',/*Demo Url*/
        ),
        'unique_prefix_pro_id_4' => array(
            'title' => __( 'Title of Block', 'text-domain' ),/*Title*/
            'is_pro' => true,/*is_pro true or false*/
            'pro_url' => 'https://www.domain.com/pricing',/*pro url*/
            'type' => 'template',/*either template or block*/
            'author' => __( 'Author', 'text-domain' ),/*Author Name*/
            'keywords' => array( 'about-block', 'about 3' ),/*Search keyword*/
            'categories' => array( 'about' ),/*Categories*/
            'template_url' => 'https://www.domain.com/gutentor-block-or-template.json',/*Json file url */
            'screenshot_url' => 'https://www.domain.com/gutentor-block-or-template.jpg',/*Screenshot of block*/
            'demo_url' => 'https://www.demo-domain.com/',/*Demo Url*/
        ),
    );
    return array_merge( $my_templates_list, $templates_list );
}
add_action('gutentor_advanced_import_templates','prefix_add_own_premium_templates');

On the pro version of your plugin/themes, allow importing templates and blocks by adding following code.

add_filter('gutentor_is_pro_active','prefix_activate_pro');
function prefix_activate_pro($is_active){
    $is_active['Author'] = true;/*Author is the block/template author name*/
    return $is_active;
}

Note: For premium template and block, you can also not add templater_url on the free version and only add template_url on pro version.