client.rb

# initialize a client
client = Faraday.new(url: 'https://lightning-2pdf.herokuapp.com/') do |faraday|
  faraday.use FaradayLnPaywall::Middleware, { max_amount: 100 }
  faraday.adapter  Faraday.default_adapter
end

# use the client to do API calls:
puts client.post("/convert/pdf", "# Hallo Welt").body

server.rb

Rack::Builder.new {
  use Rack::Lightning, { price: 100 } 
  run Proc.new { |env| ['200', {'Content-Type' => 'text/html'}, ['get rack\'d']] }
}.to_app