I joined up on xbox live gold back in 9 December 2015 specifically to get the free copy of Ryse. The following is a cut and paste from my email account from MS:
"We're sending this message to confirm that you have successfully activated Xbox LIVE Prepaid 1 month Gold Membership Card on Wednesday, 9 December 2015. Here are the details:"
So I have looked around the forums and seen that it may take up to 4-6 weeks to get the code via my email that is linked to my username. Well, it has been exactly 5 weeks so far and there has been no Ryse code arrive yet.
I hope it arrives in the next week or two as I am dead keen to play Ryse on Xbox one.
UberViktor aka 'Brett'