When you tie a subscription to your account, the first payment does not come from your card until the free 30 days are up.
Now that you have removed the card, you will not be charged on that card for any payments. The card needs to stay on the account in order for a payment to be taken.
This does not effect your subscription but it will mean that after your first 30 days you will either need to add the card again for a subscription or purchase a prepaid game time card.
I hope this helps.
The problem is, I was under the impression that I purchased game time. How can I be 100% sure that this charge will not show up later, or is not somehow currently pending?