CTA button that is only visible to some of my users

First define a function to check if user has bought product before.

// function to check product bought by user before

function has_bought_items( $user_var = 0,  $product_ids = 0 ) {
    global $wpdb;
    
    // Based on user ID (registered users)
    if ( is_numeric( $user_var) ) { 
        $meta_key     = '_customer_user';
        $meta_value   = $user_var == 0 ? (int) get_current_user_id() : (int) $user_var;
    } 
    // Based on billing email (Guest users)
    else { 
        $meta_key     = '_billing_email';
        $meta_value   = sanitize_email( $user_var );
    }
    
    $paid_statuses    = array_map( 'esc_sql', wc_get_is_paid_statuses() );
    $product_ids      = is_array( $product_ids ) ? implode(',', $product_ids) : $product_ids;

    $line_meta_value  = $product_ids !=  ( 0 || '' ) ? 'AND woim.meta_value IN ('.$product_ids.')' : 'AND woim.meta_value != 0';

    // Count the number of products
    $count = $wpdb->get_var( "
        SELECT COUNT(p.ID) FROM {$wpdb->prefix}posts AS p
        INNER JOIN {$wpdb->prefix}postmeta AS pm ON p.ID = pm.post_id
        INNER JOIN {$wpdb->prefix}woocommerce_order_items AS woi ON p.ID = woi.order_id
        INNER JOIN {$wpdb->prefix}woocommerce_order_itemmeta AS woim ON woi.order_item_id = woim.order_item_id
        WHERE p.post_status IN ( 'wc-" . implode( "','wc-", $paid_statuses ) . "' )
        AND pm.meta_key = '$meta_key'
        AND pm.meta_value="$meta_value"
        AND woim.meta_key IN ( '_product_id', '_variation_id' ) $line_meta_value 
    " );

    // Return true if count is higher than 0 (or false)
    return $count > 0 ? true : false;
}

After that Create a shortcode to display CTA if user has not bought product:

function cta_shortcode() { 
    $cta="<a href="#">Buy This Product</a>"; 
    return has_bought_items() ? "" : $cta;
}

// register shortcode
add_shortcode('cta-shortcode', 'cta_shortcode'); 

Finally you can use this shortcode to conditionally show cta to users.

[cta-shortcode]