Hi Dave,
Another thought: are your BOM components flagged as relevant for the legal regulation being checked ?
Perhaps if you flag each of the BOM components to "no control" in the product master data (under tab Legal Control ) then this will avoid the component to be checked and therefore avoid having the licences assigned to them.
Not sure that making the BOM components as not relevant still fits the requirement that lead you to activate the Legal control check at BOM items.
Regards.
Mouaz BEN REDJEB