Requirements
-Xbox LIVE Silver account
-PayPal or Credit/Debit card attached to your account
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First, you'll head over to here this link.
Step 2
You'll log in to your Xbox LIVE account on Xbox.com. You'll then be taken to the
Membership Choice page. You'll see $0.00 for one month. Hit next.
Step 3
Confirm payment with either a PayPal account or an attached Credit/Debit card.
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Automatic Renewal can be turned off without any tricks. Simply go to your account page and click the "Change" option. Enjoy!