Script needs to be stopped after 24 hours

I would like to run my script for 24 hrs, then it needs to be stopped even if processes are still going on.

Use timeout:

timeout 24h my_script

Or use at to kill at a specific time, something like this:

my_script &
my_script_pid=$!

at 13:37 <<< "kill $my_script_pid"
# or
at now+24hours <<< "kill $my_script_pid"

# optional, if you want to close the terminal:
disown

Using at can have some benefits, e.g. when launching your script via ssh and detach from the current terminal (-> disown), you can close the connection / the terminal.
But you should be aware, that if the script stops before the time is up, the PID might get reused. You might be able to find the PID with other means, e.g. ps aux or pkill myscript.sh or so.

You could also use screen or nohup with the first command.

A few alternatives based on the fact that kill 0 signals all processes in the current process group.

For example:

sh -c './script & sleep 24h; kill 0'

Or:

./script | ( sleep 24h; kill 0 )

Or:

./script | { sleep 24h; kill 0; }

Can you use crontab to kill the service

#!/bin/bash
cat <(crontab -l) <(echo "0 0 0 0 0 kill-scripty.sh") | crontab -

# do something