Payment is only made when you have finally decided to write the WILL. Once written and payment is made, the WILL document is hedged onto the blockchain, this transaction cannot be reversed as Blockchain does not allow reversal of a transaction.
You may cancel the WILL anytime and that too will be hedged on the Blockchain. As any transaction cannot be reversed, so does the payments that are made for those transactions. Hence there shall be no refund once the transaction is paid and hedged.