I found the answer: "payment_definitions": [{ "frequency_interval": 1, "amount": { "currency": "USD", "value": 0 }, "frequency": "Week", "cycles": 2, "type": "TRIAL", "name": "Two Weeks Free" }, { "frequency_interval": 1, "amount": { "currency": "USD", "value": 5.00 }, "frequency": "MONTH", "type": "REGULAR", "name": "Monthly Payment" } ] link: https://github.com/paypal/PayPal-PHP-SDK/issues/1032
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