private function _activate_addon_account( Freemius $parent_fs ) {
            if ( $this->is_registered() ) {
                // Already activated.
                return;
            }

            // Activate add-on with parent plugin credentials.
            $addon_install = $parent_fs->get_api_site_scope()->call(
                "/addons/{$this->_plugin->id}/installs.json",
                'post',
                $this->get_install_data_for_api( array(
                    'uid' => $this->get_anonymous_id(),
                ), false, false )
            );

            if ( isset( $addon_install->error ) ) {
                $this->_admin_notices->add(
                    sprintf( $this->get_text_inline( 'Couldn\'t activate %s.', 'could-not-activate-x' ), $this->get_plugin_name() ) . ' ' .
                    $this->get_text_inline( 'Please contact us with the following message:', 'contact-us-with-error-message' ) . ' ' . '<b>' . $addon_install->error->message . '</b>',
                    $this->get_text_x_inline( 'Oops', 'exclamation', 'oops' ) . '...',
                    'error'
                );

                return;
            }

            // Get user information based on parent's plugin.
            $user = $parent_fs->get_user();

            // First of all, set site and user info - otherwise we won't
            // be able to invoke API calls.
            $this->_site = new FS_Site( $addon_install );
            $this->_user = $user;

            // Sync add-on plans.
            $this->_sync_plans();

            // Get site's current plan.
            //$this->_site->plan = $this->_get_plan_by_id( $this->_site->plan->id );

            $this->_set_account( $user, $this->_site );

            // Sync licenses.
            $this->_sync_licenses();

            // Try to activate premium license.
            $this->_activate_license( true );
        }