Complex sentence: In 1991, after Lithuania's independence, it gained the status of an international airport and in 1996 it became a member of Airports Council International (ACI) and began to take part in the activities of the "Lithuanian Airports" association.
Split into simpler sentences: In 1991, after Lithuania's independence, it gained the status of an international airport. In 1996 it became a member of Airports Council International (ACI) and it began to take part in the activities of the "Lithuanian Airports" association.