That is certainly something that can be argued in court, and the case might be very strong...but you'd still have to take it to court. Something else to consider is that if the agreement isn't clear about its limitations, then it can be argued that it isn't limited. All the company has to do is send you a key to the full game when it's available and they are technically still in compliance with the agreement. It would not matter if you tell them that you do not wish to participate anymore, or that you bought your own copy, you'd still be bound.