This is not what GP asked. AFAIK, it's not legal in the EU as long as the customer has a reasonable expectation that the subscription is not time-limited, i.e.,

This is not what GP asked. AFAIK, it's not legal in the EU as long as the customer has a reasonable expectation that the subscription is not time-limited, i.e., if no time limitation is clearly mentioned when the subscription is purchased. There are often clauses in EULAs stating things like "our company has the right to terminate the subscription at any time for no reason" but these are generally void and can make the whole EULA void. Otherwise, it would be legal to sell software and simply switch it off after 6 months - or, after one month, or even after one day. Clearly, that would be fraud. The question is rather which of the EU customers will/can afford to sue Steam. My guess is they'll offer a refund for those games before it comes to a law suit.