In SatisMeter we use only one cookie in our widget and it's named sm_anonymous_id.
We use it to identify anonymous users on subsequent visits - we need it to track the user's response history and make sure we don't ask the same user twice. It is a random unique identifier and does not contain any personal data.
The cookie expires one year after it's set (the first time the user visits the page with the widget).
If you are using SatisMeter with logged-in users, there's no need for cookies. Meaning, that the cookie is only used if no userId is passed.