1. By default a user ticket(TGT) life time is 10 hours, it can be renewed up to 7 days
2. Tickets and keys obtained from the KDC are stored in a credentials cache, an area of volatile memory protected by the LSA. The credentials cache is never paged to disk. All objects stored there are destroyed when a security principal logs off or the system is shut down.
3. If you work non-stop for more than 7 days, it doesn't mean you have to type in your password again. The LSA also keeps a copy of an interactive user's hashed password. If the user's TGT expires during a logon session, the Kerberos SSP uses the LSA's copy of the hashed password to obtain a new TGT silently, without interrupting the user's logon session. The password is not stored permanently on the computer, and the local copy is destroyed when the user's logon session is destroyed.
4. However, there are changes in the background if you leave an open logon session over 7 days limit. Changes are:
1) You will get a new ticket, obviously, in the background
2) If you have any membership changes, it will be reflected in the new ticket without having you log off/log back on.
3) User Rights Assignments change will be reflected
4) If you don't force the user to log off, which could also means he/she can have access that you don't want him/her to have because his/her ticket remains valid in its lift time.