How to derive last 24 months for Keyfigure variable in APD

Hi Team,

In the Current query, we have KF is restricted with cal month variable(offset-24) to derive last 24 months data. Getting Memory issue when using this query as source in the ADP to dump to file.

Trying to get the query data using the cal month in to the staging DSO using APD first.

Now how to derive the Key fig quantity(Offset-24) to fetch last 24 months from the DSO(ADP) to the target file in the APd?

Appreciate you help

Thanks