If you're on 11.2.0.4+ take a look at Flashback Data Archive. This tracks all changes to tables for you automatically!

To use it, just create an archive and add your tables to it:

create flashback archive app_archive 
  tablespace users retention 7 year;
 
alter table customer_addresses 
  flashback archive app_archive;

Storing data in the archive is handled by a background process. So the above fails, you won't see an error in your client:

https://blogs.oracle.com/sql/entry/why_you_can_get_ora

Keep an eye on the alert log!

You can then see changes as far back as the retention time using flashback query. For example:

/* What did the data look like yesterday? */
select * 
from   customer_addresses as of timestamp sysdate - 1;

/* What between yesterday and now? */
select * 
from   customer_addresses 
         versions between timestamp sysdate - 1 and sysdate;

If you're on 11.2.0.3 or lower this is a separately licenseable option. So you could pay for it... or just upgrade ;)

12c also includes an number of enhancements. This enables you to track more details about who changed rows, when, etc.:

https://oracle-base.com/articles/12c/flashback-data-archive-fda-enhancements-12cr1