deleting entries from nt4.0 license mana

under nt4.0 per seat license scheme, using
license manager, how do I delete an entry that is no longer valid and keep it from returning. After deleting entries everything is fine until I reboot the server then the deleted entries return. Where must I look to completely remove them?
Also the combination of “user name/computer name” seems to generate a license entry, is there anyway to control this so that only one license is used per seat reguardless of who signs onto that seat?