I did purchase a nRF51822-DK and did not find the product key. Where is it hidden?
IIRC it was printed on the packaging when I bought my DK. That was a while ago so things may have changed. I'd at least give a look at the boxes inside the kit.
Do you mean EK? In that case, on the plastic bag.
It should be written on the box or the anti-static bag. If you didn't get a key, ask the Nordic support team: http://www.nordicsemi.com/eng/Support/Contact-Support-Team
On Nordic's Anti-Static Bag Label at bottom
Agree with Paul. That's where mine was. -e
