How does the swtor subscription work in steam?

I bought a 30 day subscription for star wars the old republic via Steam, after which I received an email from them (not steam) telling me that they'd charge me every month to renew.

Is that true? Will I automatically be charged through steam? (BioWare doesn't have my CC info)

I thought it was a one-time 30 day buy (since you can even buy more time in one chunk)

For the record I plan on keep subscribing for a while longer but I'm unsure if I should manually buy more time, wait to be charged automatically, or what

Solution 1:

EA/BioWare's direct subscription options are also for different chunks of time (you save a couple bucks per month, they get you to subscribe for longer). This is likely exactly the same and they just have Steam charge you. However, I'm finding some conflicting information about whether Steam's variety is actually non-recurring.

You can always cancel the subscription now, and decide what to do once your current 30 days are up. If you plan on playing more, you may want to do that and just pick one of the longer plans.