Whilst the audit policy created by CREATE AUDIT POLICY is database-wide, it is applied to individual objects or roles by the AUDIT statement. For example, to audit statement executions (successful or otherwise) against a particular table:
CREATE AUDIT POLICY allexec CATEGORIES EXECUTE STATUS BOTH;
AUDIT TABLE mytable USING POLICY allexec;
To audit statements executed by a particular role:
AUDIT ROLE somerole USING POLICY allexec;
The reason for all the COMMITs is that, as the docs note, "[a]n AUDIT-exclusive SQL statement must be followed by a COMMIT or ROLLBACK statement...". See audit policies for more information.