a freelance client ghosted on the final invoice and the one thing that saved me was a stupidly specific milestone clause I almost didn't bother adding

Net-30 came and went, emails stopped getting replies. The contract had a clause that unpaid milestones over 15 days revert all delivered work to a non-commercial license. Sent that one line, invoice got paid within the week. Never skipping that clause again no matter how small the project feels.