Registering Navman S/ware

[Nipper]

Help Please , I just sold a Navman 3400 jacket +software ,the buyer now tells me he is not able to register software as it is only good for one piece of hardware ! . This worked great on my 3760 which I still have .can anybody help me with this or any way round it ?
PS I was already a second user of this product and had no problem registering .. Thanks in advance Paul

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