Dear Torfinn & Jeff,
PLAV is for the plugin, not for the full Deluxe-plus-Civil-plugin installer. PLAV should continue to work for the 2017 version of the Civil Design Suite plugin. For the full installer, TCKT, TCKU snaks should also continue to work. So, be sure you are using the right SNAK for the right installer.
TCxx are TURBOCAD serial numbers; PLxx are PLUGIN serial numbers.
Please use following:
Civil Design Suite:
TurboCAD Civil 2017:
Please let me know if you still need more information!