What actually worked for me was:
download ngrok normal/free service, and put it in your path download the authkey once you create an account, and set it w/ "ngrok authtoken " => this creates a file under your home/.ngrok folder
setup a service with nssm (install nssm from Admin\PowerShell w/ choco install nssm):
nssm install ngrok
in the service setup window, add executable "cmd.exe" w/ parameters: /K ngrok tcp 1234
in the newly installed service, change the login user to be your current one. this way, when service starts, ngrok can fetch the auth key from the user's home dir.
is there a better way?