Hello, I'm CrazyKilla.

I know you have to pay $15 a month to play ESO, but do you have to pay EVERY month?

Can I for example decide that I won't play ESO for a while and not pay the monthly fee, and then when I want to play I get like 30 days to play the game?

How does this work?

If you pre-ordered, you get the first month free, but other than that I don't think there is anything like that. You have to pay $15 every month.

Say you buy a month (30 days) of sub fee on 1 may, you will be able to play from the 1st till 31 may.

if you buy it on the 1st, then not play for a month, logg in on the 2nd of june, then you will not have sub left. for it lasts for 30 days.

hope this clarifies. i have been known to explain thing i understand fairly well fairly poor

It sounds like maybe you're asking if the time on your account ticks down on days when you are not logged in? If so, then yes. It does not matter whether or not you log in. When you pay for an amount of time, it starts from that time (or from when your previous time is done, if you are already subbed), and goes continuously until it's over. Unless you use a game time card, it will automatically renew your subscription and charge the card you have on file again when the current sub is over. You can stop that by cancelling your sub before it renews.

You could play the 30 days that come with the game and not re-sub. Then in a few months pay $15.00 and you would get 30 days from that time.

Another way to interpret you question is what happens when you don't pay. I'm sure ESO is just like every other MMO that when your subscription runs out you will lose access to any membership benefits until you subscribe again. Since ESO is currently a membership only MMO you simply will not be able to play the game. Your character and all of their stuff is safe but you can't access any of it. This is true unless ESO actualy has items that degrade over time with out use. UO (back in the old days anyways) required you to log in once every 5 days otherwise your ship would fall apart. Got busy and logged in on day 6 and my ship sank.

I have a seperate question in regards to membership though. Is the only option to pay per month? Can I buy a 3, 6, or 12 month subscription at a reduced cost?

They have stated that there will indeed be multi-month subs with a discount, but have not as yet shared any specific information on them.

And, until we hear anything about that, we are not discussing the payment model.

And, OP, yes, the free month with purchase starts the moment you validate the game. So, plan accordingly.