If you need to run your bot 24/7 (with no downtime), you should consider using a virtual private server (VPS). This is a list of VPS services that are sufficient for running Discord bots.
- New York data centre.
- Great affiliate program.
There are no reliable free options for VPS hosting. If you would rather not pay for a hosting service, you can consider self-hosting. Any modern hardware should be sufficient for running a bot. An old computer with a few GB of ram could be suitable, or a Raspberry Pi.