database flow

Just a minor clarification.
products database holds products info.
they are copied into the order_products database as long as orders are issued.
are those records added up endlessly?
or are they removed upon some event like an admin clean option or upon delivery?
or it requires manual intervention?
thanks

Added forever - - because as a customer I can come back and view my past purchases

Thanks a lot. I just wanted to make sure, before making some changes into the code.
I am working on a Mall system, where products are linked to stores, and i want to make sure which products have been ordered by which store and from there which items have been shipped, cancelled, etc.