If he said, "No cure no pay" - as in your heading - I imagine he/she meant, "Unless what you're doing results in a solution to this problem, you won't get paid for the time you spend on it." If he/she said, "No cure no pain" - as in your question - I'm at a loss to understand. Are you sure he/she didn''t say, "No pain no gain"? In other words, "You often have to suffer in order to achieve something."