public function alerts( $alerts = array() ) {

		static $showed_invalid_message;

		// If user can't manage it, or we already showed this alert abort.
		if (  ! current_user_can( 'manage_options' ) || $showed_invalid_message ) {
			return $alerts;
		}

		// If this alert is already in the list of alerts, abort.
		foreach ( $alerts as $alert ) {
			if ( 'license_not_valid' === $alert['code'] ) {
				return $alerts;
			}
		}

		// If this license key is not empty, check if it's valid.
		if ( ! empty( $this->license ) ) {
			$license = get_option( $this->item_shortname . '_license_active' );

			if ( ! is_object( $license ) || 'valid' === $license->license ) {
				return $alerts;
			}
		}

		$showed_invalid_message = true;

		if ( empty( $this->license ) ) {
			$alerts[] = array(
				'code'        => 'license_not_valid',
				'message'     => sprintf( __( 'One or more of your extensions are missing license keys. You will not be able to receive updates until the extension has a valid license key entered. Please go to the %sLicenses page%s to add your license keys.', 'popup-maker' ), '<a href="' . admin_url( 'edit.php?post_type=popup&page=pum-settings&tab=licenses' ) . '">', '</a>' ),
				'type'        => 'error',
				'dismissible' => '4 weeks',
				'priority'    => 0,
			);
		} else {
			$alerts[] = array(
				'code'        => 'license_not_valid',
				'message'     => sprintf( __( 'You have invalid or expired license keys for Popup Maker. Please go to the %sLicenses page%s to correct this issue.', 'popup-maker' ), '<a href="' . admin_url( 'edit.php?post_type=popup&page=pum-settings&tab=licenses' ) . '">', '</a>' ),
				'type'        => 'error',
				'dismissible' => '4 weeks',
				'priority'    => 0,
			);
		}

		return $alerts;
	}