Use watermarks for unpaid designs!!

A client reached out to me in March. Found me through a referral, someone I'd done work for back at UNEC and apparently she spoke well of me. She needed a full brand identity: logo, colour guide, social tem, the works. We talked twice on the phone. She was cool and she seemed like the kind of client that would actually use what you delivered properly. Like stuff you'll see on IG and feel good about your work.
I sent a proposal. Charged 280k, she priced it down to 220k and I accepted because e been start dey red and I kind of liked the brief. We agreed 50/50, 50 upfront, 50 on delivery. She paid the first half within 24 hours. I started thinking, this one fit dey different.
I delivered in three weeks. Full package, properly organised, with a brand guide document that I spent two days on because I wanted to be proud of it. She acknowledged receipt and said she'd review and get back to me.
That was April.
By May I had sent about 4 follow-up messages. By June, two more. I tried to make sure I was polite and each one sounded more tired than the last. She replied sometime in May to say she'd been "swamped" and would revert. Lie lie!
In July, a friend sent me a screenshot. The logo was on her website. The colour palette was consistent throughout. The social media templates were being used, posted three times a week, doing numbers.
To be honest, the anger I felt was not just about the money, though it was also very much about the money. The specific cruelty of watching your work out there doing its job, while you're being pretended out of existence by the person it's doing the job for.
I sent one final message. Not emotional. Just: "I can see the brand identity is live. Please settle the outstanding balance of 110,000." Delivered. Never read. Or read and ignored, WhatsApp will let you decide which version hurts more.
Now I've learnt. I have started adding a clause to every contract - final files are delivered in draft/watermarked form. Clean files release upon final payment confirmation. This lesson cost me 110k tuition. I don pass am for free. You're welcome.