vertica license downgrade/upgrade

If it is a demo database, I recommend going with CE license from the beginning to avoid license expiration issues, such as the database refusing to run queries until you install a valid license.
We don't let you downgrade from an Enterprise license to a CE license, not even if you restored the database to a different environment. You will need to get a new license to continue using the demo database, and so forth. Seems like not worth the extra work for a demo database. CE licenses are perpetual.

Thanks Cary. We already setup demo using 45 day license. Was wondering i can use drop license to remove the license and then community license will work. if it crosses 45 days Database wont start ? how to change license to sue a new trial license next year after license expires?

You need to have at least one license installed in the database, which means that you cannot drop the current license you have. After it expires, you will be able to restart the database, etc. but it won't let you do anything useful. You need to install a new (non-CE) license at that point. Then you can drop the expired license. You may be better off re-creating your database and use CE license only in the long term.

Thanks Ariel for your help in clarifying our doubts