One should be able to authenticate logins through Apple Watch, but in my case the watch asks if I want to reject the login or "reject" it but in another language. I want to report this bug. But it seems as if you aren't premium you can't. Is this...

LastPass Support

... correct?

LastPass Support

Hello @Johan Lindén​

Welcome to the LastPass Community.

There should be no difference in your LastPass experience on Apple Watch regardless of the account status.

You may update the Language setting under the Advanced section of your LastPass mobile app by following these directions.