What happens to my LEDs if I sign out or my membership lapses?

Your lights keep working. Signed out, or with a membership that has lapsed, the LEDs run on the defaults the plugin ships with. They do not go dark and the plugin does not switch itself off.

What you lose is the membership features on top, such as Specific RPMs, which mirrors each real car's own rev lights. The rev bar itself still lights, using the generic behaviour.

The plugin's LED page says which state it is in rather than leaving you to guess.

Signing back in restores your car data and your settings. Nothing needs rebuilding.