I just started a new project in which I want to use the Stack Exchange API. I will need users to authorize the app to read e.g. their favorited tags. Therefore I need an API key, so I have to register my app, right? 

But I am just starting development and can't fill out the form under https://stackapps.com/apps/oauth/register because I don't have a live system right now. So what should I do?