How to get latest record weekly within an SQL statement

I'm trying to export the latest records from SQL Server 2005 database once weekly. This is my table:

agent_name  date          ID
ALEX        2015-05-25    13
ALEX        2015-05-22    13
ALICE       2015-05-24    10
ALICE       2015-05-26    10

How to create output table should like this:

agent_name  date          ID
ALEX        2015-05-25    13
ALICE       2015-05-26    10

My sql script:

SELECT a.agent_name,  
       a.date, 
       a.ID 
FROM Payment a 
INNER JOIN agentmaster b ON a.ID = b.ID2 
WHERE b.agent ='Y'
AND a.date >= DATEADD(day, -7, GETDATE())