Excellent Service.
Could not be any easier:
1- Make order and pay.
2- Receive e-mail quickly to verify my phone number.
3- Receive my code.
4- Redeem code, and now I have a year worth of Xbox Live on my account.
5- All of this took less than five minutes.
Also, the support service is excellent. When I made the payment, I didn't get the facebook discount applied. Send an e-mail, receive a response quickly the same day and also the amount refunded to my PayPal account.
I had a better and fastest experience (better price also) buying my Xbox Live Membership from CDKeys, than from other places or MS directly.