Rails Devise - current_user is nil

Rails Devise - current_user is nil

For some reason, current_user returns nil in my model-less controller
(Subscriptions). I have found nothing on the Internet to justify this
behavior...
class SubscriptionsController < ApplicationController
def new
...
end
def create
current_user # returns nil
end
end
I can provide more code, but I'm not sure what would be useful.