Yep, the cards are 'one shot' programmed, and so a second-hand one is useless. Wherever you source your key, it must be a blank one (or one specifically pre-configured to your car by Renault) and then it must actually be paired to the car by someone with the diagnostic computer.
Whether or not blank cards from
will still work is a bit of a grey area at the moment. The best thing to do is get it from the dealer's mouth - are they prepared to program a blank card that you provide yourself? If so, then go for it.
When it comes to cards and reprogramming, shop around a few dealers (though obviously if you don't have a card at all, moving the car around is going to be tricky.) Prices tend to vary quite wildly. It's probably well worthwhile getting a second card at the same time - this will double the cost of the parts, but won't cost any more for programming.
If you still have the original card but it's broken, be sure to save the emergency key that's tucked into the corner. The new card will come with an uncut blank key and you will have to pay extra if you want the key to be sent away to be cut. If you already have one, it'd be better to hang onto that.