Can not buy a subscription on xbox

You can no longer purchase a 12 month subscription through Xbox, but you can still buy them as a prepaid code through other retailers. Otherwise, through Xbox you can buy a 1 month or 3 month Gold subscription.

I don't know (don't remember) if prepaid credit can e used to buy Xbox Live Gold or Xbox Game Pass Ultimate subscriptions, but, you can work around this issue buying a prepaid for code for one of this subscription to gift with the console.

Yes you can now buy an annual subscription for Xbox Game Pass. Microsoft is apparently providing fans with a cheaper long-term offering for its Xbox Game Pass subscription service, giving gamers the option to buy a 12-month subscription for just $99.99.

You can buy an Xbox Live Subscription with your credit card, or buy a code in a phisical store and redeem it

You can buy it as a monthly or 3 month subscription through Xbox, or you can buy prepaid codes at a retailer. There's no way to pay as you go.