I bought two four day museum passes about two weeks ago when we touched town in CDG. Plans changed, and we never validated them / started them / used them.
I sent an e-mail via their website two weeks ago but have not got a response.
I feel like these are good for as long as they remain unchanged in duration (2, 4, X days). But is there a set 'the passes must be validated within N days of purchase' guidelines?