With the next release(TBD) we will require any Pipe that uses the Flickr Module to use an API key. You can obtain the Flickr API key here: http://www.flickr.com/services/apps/create/apply/. It’s easy to get a key and please get it ready for when this change happens. You can also use the Private String Module to make sure your API key is not viewable to the public as described in the screenshot below.