Auto-renewing subscriptions are common enough that confirming a genuinely one-time purchase is worth thirty seconds before entering payment details.
What a genuine one-time checkout looks like
A clearly labeled one-time purchase option, distinct from any "subscribe and save" toggle, with no recurring billing language in the fine print near the payment button.
If the terms aren't obvious
Contact customer service directly and get written confirmation of the billing terms before entering payment information, rather than assuming based on the displayed price alone.
💡 This is general educational information, not personalized medical advice.