2 ways at least
an EU airport or regulatory authority follows up the foreign aircraft oversight, based on input from persons involved in a flight or two.
or an employeee claims in hiis own EU country, a sum of money owing, and obtains a court lien, to padlock the asset to ensure settlement.
ie has the eurocontrol bill been paid.????
or airport bills outstanding....
all handling companies billsall up to date.
glf