Purchasing second hand HD accel cards

[fm_xtk]

Hello,

I am thinking of picking up a second hand accel card (PCIe). One was offered to me that was part of a HD3 bundle but it has apparently never been registered.

Will I be able to register such a card to myself or will digi only accept it as part of the bundle it originally came with (therefore locking it to that HD3 system)?

Also, not that I care too much about plug-ins but will I be eligible to get HD2 plug-ins if I register another card (I am on HD1 at the moment).

Thank you very much