Getting kids to clean up after themselves?

My step kids live with us full time, they’re 12 and 13 1/2. They’ve always had problems cleaning up after themselves, even at their moms house. I have asked so many times to pick up their messes. Rinse out your cereal bowl, throw away wrappers and empty cartons, pick up your towels, etc. We don’t ask them to do a lot. They have a daily chore chart with like 1-2 things on it. I STILL have to remind them to do it at times. My step son left his socks on the living room floor and I let them sit there for a month before my step daughter pointed it out to him. I’ve asked nicely, sternly, grounded them for it, you name it. Yesterday I just lost it because he left salt spilt all over the stove, didn’t rinse his cereal bowl (I’m talking cereal caked onto the bowl bc he doesn’t finish it), and left an empty snack box in the cabinet. His dad had a long talk about how he needs to step up and clean up after his own messes. It’s not like we ask him to clean up after everyone, just him. So he grounded him from his phone. Then I wake up to more messes this morning. I don’t get it. I’m pissed off and exhausted. Im 35 weeks pregnant and tired of cleaning up after everyone. He wants to move back in with his mom and my husband won’t let him. I wish he would at this point honestly. I do SO much for them. I praise all the good things they do and reward it. Yesterday I got their report cards and they got straight As so I gave them $20 each and ice cream after dinner. He never says thank you unless he’s reminded. He acts like we’re so mean to him but he has it so easy here. I’m just stuck and frustrated. It’s just so built up because it’s been an ongoing issue for over a year now and hasnt gotten better.