Ranger!
As the migration / transfer process ended, players who still have the Nexon launcher to play the Combat Arms will not be able to use it again. If you try to use it, the Nexon launcher will ask for a 16-digits product keys. The reason why the Nexon Launcher cannot be used again is because the Combat Arms have been removed to Nexon and fully handed to VALOFE.
To solved this issue, players who still have it should uninstall their old client and launcher then download the new full client of Combat Arms in VALOFE Sites.
Full Client Download:
https://combatarms-r.valofe.com/download
If you still have questions and inquiry, please contact our customer support.