http://quickexpgxtyxalax7kfy4f3mntpjpqrfizwksogvtsgehkbkttuosid.onion/blog/price-prediction/monero-payment-step-by-step-guide
For the Monero GUI wallet, open the app, head to the “History” tab, click your transaction, and hit the “P” icon to peek at the payment proof details. Got a third-party wallet? Some don’t share Tx keys, so you’ll need to ping their support team. Always set your wallet to save Tx keys by default—without it, proving an XMR payment is a no-go.