1. It means that your subscription type will be recurring (Your paypal account will be charged every 30 day)
This means that the first month will be 20 USD, the next will be 15 USD only.
You can cancel the subscription anytime whenever you desire.

2.All cheats got 1 Month - 3 Month -6 Month. If you select more months each month will costs less.

3.If the cheat is down for more than a week then yes.