How long to pay GTC?

Excuse me, could you please clarify what you mean by "GTC" in the context of paying for something? If you're referring to a Good Till Cancelled order in cryptocurrency trading, then the payment for such an order is not a straightforward process as it's more of a trading instruction. However, if you're asking about the duration for which a GTC order remains active, typically, a GTC order stays open until it's either executed, cancelled by the trader, or until it expires based on the exchange's policy. There isn't a set time frame for how long a GTC order will last, as it can vary depending on the exchange's rules and regulations. If you're asking about paying for something using cryptocurrency and the question relates to transaction confirmation time, then it can vary significantly depending on the cryptocurrency and the blockchain network it's built on. For instance, Bitcoin transactions can take anywhere from a few minutes to several hours, while some other cryptocurrencies like Ethereum or Solana can confirm transactions much faster. Could you please provide more context or clarify your question to help me give a more accurate answer?