Complex sentence: At the end of the programme, he ranked 9th and officially became one of the 11 members of Wanna One, subsequently becoming an inactive member of NU'EST until Wanna One disbands in December 2018.
Split into simpler sentences: At the end of the program, he ranked 9th and officially became one of the 11 members of Wanna One. Subsequently, he became an inactive member of NU'EST until Wanna One disbands in December 2018.