Deleted

as far as i know yeah you can .
but can take some time until they get added because they are not high priority if i remember right .

Yup, I've done it recently, It's easy to do, just create a ticket

View attached image.

Yep, they can be easily added. They should return with the last known price.

I'm curious... if you have these keys for delisted/banned games, what's the chance they even work still?