Yes. If you have a subscription pass (either a Premium or Frequent Pass), you automatically join Club Eurostar. 

- As a Frequent Pass subscription holder (6 and 12 months), you gain direct access to Avantage tier.
- As a Premium Pass subscription holder (6 and 12 months), you gain direct access to Etoile tier.

As a subscription pass holder you benefit from reduced prices and flexible ticket conditions, for travel between Belgium, France, The Netherlands and Germany.