I can't use a 2 day or 14 day gold cards

Try checking your subscription at http://commerce.microsoft.com to make sure it does show your gold has expired or that there isn't another error. If it does show your gold has expired, you'll want to try contacting
support. 1-800-4my-xbox if you're in the US/Canada or http://support.xbox.com/contact-us

The 14 day trial doesn't give you the "full" gold benefits.

Some games can't be played online with a 14 day trial card.

Hi. I used the 14 Day Gold code from my Xbox One but I wanted to buy a new gold sub in 1-2 days. :-/

If this is no "real" gold I won't get Reward points for buying things on the marketplace?

There should be more details about this on the Trial Subscription cards. It does not say it has limited features, just limited to 14 days.

Hi,

You don't have any sort of a free trial attached to your account. If you were offered a 30 day trial on the console dashboard you'll need to add a payment method in order to take advantage of it.

If you redeemed a trial code like a 2 day or 14 day trial, or even a 30 day trial code from a redemption card then you wouldn't need any sort of payment details. The 2 day/14 day card doesn't give you gold status but lets you play online for the stated days
(2 or 14 days, depending on what you redeemed), or 30 days (which will give you gold status) if you redeemed it from a gold subscription card.

That is not an official Microsoft website. 2 day, 7 day, and 14 day cards are given as trial subscription with games and consoles. They are not full gold subscriptions. They only give you access to some benefits of online multiplayer, not all of the gold
benefits.