How do I make the blue soul work?

So I am working on an Undertale AU and I am having trouble with the blue soul because in Undertale, you can't just hold the jump button and stay on the top, and I can't figure out how to fix mine since if I just hold the w key, I can just hang on the roof, so I need help so that you can't just spam the w key.

I also can't seem to figure out how to post the code so you can look and when I drag the screenshots, it just shows the screen shot and nothing else, not even the send option.

Please describe the mechanic as if someone hasn't played Undertale

Basically I want it so that if you press the w key, which makes you go up, your character goes up, but I also don't want it to continue going up, so I want it to be like if you threw a ball in the air, it slows down as it goes higher and it will eventually go down. So I want it to go down once the character hits the roof of the box it is in, even if you are holding down the w key, and I also want it so that if you stop for a bit and then press the w key you will NOT go higher until you hit the ground. But how it is right now, you could just hold down the w key and it will not start to fall until you let go.

The logic that forces it to go up when you hold down W, have it happen only when a variable is true. Set this variable to false when you hit the top. When the variable is set to false have it move down.

Thank you, you saved me a bunch of time and now I discovered new techniques that will solve some problems that have been bugging me

Nice, glad it's resolved

So I am working on an Undertale AU and I am having trouble with the blue soul because in Undertale, you can't just hold the jump button and stay on the top, and I can't figure out how to fix mine since if I just hold the w key, I can just hang on the roof, so I need help so that you can't just spam the w key.

I also can't seem to figure out how to post the code so you can look and when I drag the screenshots, it just shows the screen shot and nothing else, not even the send option.

it all depends on the way you set the collision and the jump in the first place. i could help if you want.