Deniz,
It is not common to archive the outputs of MM documents.
I will assume that your printed output uses the typical method of sending the output to a spoolfile, where it is then output to a printer attached to your SAP system. If you wish to do actually archive these images, you will have to speak to your Basis team to find a way to save and archive selected spoolfile entries.
It is much more common to archive the MM documents themselves. Even after you have output an image of an MM document to the warehouse, the document itself usually remains in SAP tables, available for online review (and optionally for re-output). In general, they remain there indefinitely until you take special action to remove them.
Most companies establish archive policies about such matters. Never make any archiving decisions on your own! Instead, you should at a minimum consult with your local Finance and Controlling business representatives. Setting archive policies is often done through establishing interdisciplinary teams. These teams at a minimum need to have members that are cognizant of any legal requirements that may exist in the locality.
Best Regards,
DB49