Charges. Card and PayPal: $10 on the day you join, then on the same day each month until you stop. Crypto: once, for the months you pick; a month is 31 days. Stopping ends the charges at once; the time already paid for stays open and is not refunded. Paying again before your date adds to it.
Receipts. Stripe and PayPal email a receipt for every charge. NOWPayments shows the transaction on its page and on the blockchain.
Fees. The payment companies keep part of each payment: Stripe and PayPal about 3% plus 30 to 50 cents, NOWPayments about 0.5% plus the network's fee. Crypto leaves the most for aule.dev.
What is kept. Under your key, the server keeps how you pay, the subscription's number at the payment company, the date you are paid through, and which payments went on the key, beside what you keep in Strength and Lists. No name, email or card. The payment company keeps what it asks you for.
How renewal is checked. When your paid-through date passes, the server asks the payment company once whether the subscription is still on. If a card fails and Stripe is still trying it, you stay a member while it tries. A crypto payment counts once it is confirmed and paid in full.