A lot of times the MDX query needs to look at current date/today date/system date as the reference member. There is no function equivalent to TSQL getdate(), but you can use the following piece of cide snippet to solve the purpose:

StrToMember(“[Date].[Date].[” + Format(now(), “yyyyMMdd”) + “]”)

As an example, if you want to see the Sales for the last 7 days from the system date:

 [Measures].[Sales]  ON COLUMNS,
 LastPeriods(7,  StrToMember(“[Date].[Date].[” + Format(now(), “dd-MM-yyyy”) + “]”) )  ON ROWS
FROM [Cube]