Some say they don’t keep logs, and you’d have to trust that. Note that this same caveat applies for a VPN provider promising they are running diskless endpoints. Or that they don’t have some third party monitoring their stuff even if diskless. Or that a law enforcement agency can’t come along with a warrant to require them to monitor an account’s activity moving forward, even if logs are not possible.

If your online activity justifies this level of paranoia, there’s probably no meaningful protection available for your wants in practice. If your provider is operating in a jurisdiction that is problematic for your online activity, they can probably ultimately be compromised. If you are just using it to access a different country’s streaming library, you probably don’t need to be that paranoid. If you are trying to disguise illegal activity that is illegal in the jurisdiction of the VPN endpoint, well you are likely boned with logging or not.