Hi,
Generally, Prism requires you to log in at least once in order to authenticate the user.
When you start Prism for the first time with no internet connection available, Prism goes into "Offline mode" which gives you 30 days to work with the product, after which you will have to log in at least once.
After logging in once, you can keep working off line for as long as your license is valid.
Thanks,