I just started playing World of Warcraft, I am on the Starter Edition, which allows you to level up to level 20. After you reach level 20 I know you need to buy the actual game, but when you buy the game to you also have to subscribe to it?
You can buy wow gamecards instead of subscribing if you don't want to (or can't) use a credit card to subscribe. You do have to have a credit card though to activate your account, which won't be charged if you cancel the subscription right away.
Keep in mind that you are not billed for the first month of the game. Thus, if you want to set up your account immediately, you can use a credit card. Then you can easily change your payment method at any time during your free month, before your paid subscription starts.
Also you can find online stores that sell wow gamecards with a discount which can be a real money saver.
If you plan on continuing to play: Yes, You can pay online for 15$ per month or go to a store (eg. Target) and buy a 60 day gametime card for around 30$.
If you wish to stop playing If you do not pay, then the account will stay dormant until you pay for more time.
If you are talking about paying immediately after you buy the starter pack You get a free month of gametime with the pack, but after it runs out your account will go dormant until you pay for more time.
Hi When you have bought world of warcraft you can play until 1 month past then you dont need to buy another world of warcraft, you can just buy the subscription after you have bought world of wacraft then you can play 1 month, if you want 3/6 months it means you need to pay 3/6 times more but with 3/6 less euro,dollar e.t.c.
This is a buy and subscription based game, so yes, you need both if you want to play without trial restrictions.
Buying the base game
You can buy the game online or in a physical shop. Any 'vanilla' version of the game will do. That is: the original game, the original battle chest or the current battle chest, as any version will automatically be upgraded to the 'base game' which always* has all expansions besides the last one. Buying the base game adds 30 days of game time to your account.
Buying the expansion
You will always* only have to buy the last expansion, as all previous automatically get added to the base game when a new one comes out. Expansions add no game time to your account. You need the expansion to access it's exclusive content. You can play the game without it, though.
You can play the trail version of the game until you add game time for the first time. Should your game time expire, your account will be playable under veteran conditions.
You can prepay your game time or set up a subscription, so you will never run out. The first has the advantage that you won't forget to cancel, the second will never have you run out of game time.
You can also pay for game time with ingame money. The amount you need is rather high for a new player, though.
*Since around 2012 till as of writing it has been this way and it will stay this way for the foreseeable future.