For subscriptions, you make your purchase as normal and it will automatically rebill your card the next month and send you your next box (or after 3 or 6 months, depending on your plan.
Naturally, you can cancel at any time before your next box is dispatched. You can do this from your account at https://www.bluecoffeebox.com/customer/account or simply ask us. It's very easy.
If you want to purchase a single bag you can order as a "gift" and for 1-month.
Note that Gift Subscriptions do not automatically renew.