Can I use steam keys to create giveaways?

as long as its not an exploited key or a key from a bundle, your fine.

You can, just make sure the key isn't from a bundle or exploited or region restricted.

If it is region restricted be sure to point that out in the giveaway.

you can use keys, as long as they are legit and not from a bundle or exploited in some other way.

(ninja'd!)

You can, only after reading this.

What those guys said.