I have been recently been exploring the creation of ranking bots for group management on ROBLOX. But I have run across an issue, whenever I log in/out of the bot account the cookie always changes so the old one can’t work because it already expired. I have tried using the new cookie but after I get it, I get logged off and it will not work anymore.
If anyone has a way to fix this please let me know!
There nothing you can do about that, Roblox will always refresh the cookie for security.
Mostly to keep the cookie you need to never log out or log in.
What do you mean by “never log out or log in”?
I read that, sadly it didn’t help with my issue, thanks though. 
I don’t think there is a solution for it, the cookie login doesn’t support glitch and heroku, you can run it on glitch but it expires in an hour or so.
Oh okay! Is there anything you recommend other than glitch or heroku that works?
I know this is an old post, but I wanted to give some information that would help. Whenever you log into an account, the .ROBLOSECURITY key’s value usually changes as a security measure. The best way to avoid this is by not logging into the account after you have set up the initial cookie, and if you are using a module to automatically refresh the cookie like noblox.js, then I recommend keep your project active using an uptime service. Glitch doesn’t support uptime services, and Heroku’s built in uptime service isn’t always reliable. My recommendation for doing things related to this is repl.it and UptimeRobot (I am unsure if those links are blocked). They are great alternatives when keeping the project active, and to ensure that your cookies intact. The problem you mentioned is happening because your project went inactive after a certain period of time. Whenever you keep your project active often with a 5-minute interval request, even one cookie should work for months! I hope this has helped with your problem.
Edit: Make sure you store the initial cookie in an .env file too! Repl.it projects can only be private if you pay for a subscription; however, all you have to do is just add your initial cookie and your autopromotion bot should be fully functional for months with frequent requests!
This issue of yours genuinely just saved my account. Recently I fell for one of those .har export scams. Thankfully, a friend of mine told me to secure sign out of all sessions, and log in and out again.