Does the app password have a temporary validity period and need to be changed from time to time? 

[Answer] YES, the password is valid for 90 days, after which time the system forces it to change. When the password expires, at the very first login, the system will force you to change it, even if you have not logged on to the system for a much longer period. 90 days is counted since the last password change, so if you change your password yourself, then this time is counted from that point on.