Do you have to pay for Box sets?

Excuse me, I'm a bit confused about the pricing structure for Box sets. Could you please clarify whether there's a fee associated with purchasing or subscribing to Box sets? I'm interested in learning more about the cost implications before making a decision. Is there a one-time payment, a monthly subscription fee, or is it perhaps included as part of a larger package? I'd appreciate any details you can provide to help me understand the financial aspect of acquiring Box sets.