Читаем у них на сайте:
(http://www.thalys.com/fr/en/practical-t ... ng-tickets)
Ticketless - You have the freedom to travel without a ticket!
With Thalys Ticketless you can travel without a paper ticket to all Thalys destinations.
Ticketless in a nutshell:
For Ticketless journeys, simply specify your surname, first name and e-mail address;
no need to collect your ticket at the station, to receive it by post or to print it out;