Sorry, wrong.
The card only needs to be paired with the box for premium channels - that is movies and sport. If it is a freesat card or carries only non-premium channels -Discovery, Gold, etc - then once activated it will work in any box. provided the users does nothing that makes it want to phone home whence it may object.
I suspect the problem here is that it is a HD card being plugged into a non-HD box. Simple solution is to get a Freesat card or failing that a cheap (non-Sky) Freesat box (about £40 at Argos.)