There are many indications to show that your order is a subscription order:
A. When you click "add to cart".
You are informed that this will be a subscription, which means that it will be shipped every month (depending on the product). Worry not, you can cancel anytime.
The date of the next shipment will also be indicated.
B. When you proceed to click on "Secure Checkout"
You will be directed to the checkout page. Here, the Order Summary indicates that the order will be shipped every 30 days:
C. When you enter your shipping address
You will be directed to the next page to enter their billing details. At the bottom of the page, you will be reminded that this is a subscription:
Once you confirmed by clicking "Place my order", you will be sent a subscription activation email. The subscription activation email informs you that the product will be shipped every 30 days and that you will be charged accordingly.
If you want to avoid being charged on a monthly basis, you should cancel your subscription 48 hours before the next billing date. Here's how you can access your account to view billing date and then proceed to cancel your subscription: