New security feature in Oracle 12.2: INACTIVE_ACCOUNT_TIME

A profile in Oracle 12.2 can now be configured with the setting INACTIVE_ACCOUNT_TIME, which specifies the maximum number of days an account can remain unused. Unless a new login occur within the specified number of days, the account will be automatically locked.

If not set, any custom-made profile will inherit the setting of the DEFAULT profile, which is UNLIMITED.

Syntax:

CREATE PROFILE my_profile LIMIT
INACTIVE_ACCOUNT_TIME 30;

ALTER PROFILE my_profile LIMIT
INACTIVE_ACCOUNT_TIME 30;

Sources:
Oracle 12.2 New Features guide

Automatically Locking Inactive Database User Accounts

Oracle streams being terminated with Oracle 18c

As noted in the "Desupported features" section of the Oracle 18c documentation, Oracle Streams will be terminated in with the release of Oracle 18c.

For replication, Oracle Corporation encourage their customers to use GoldenGate.