Will answer in english, and if you have trouble, will forward you the answer privately in portuguese.
Question was: How to develop locally registering keys when using localhost ?
Create the keys for your own domain, and even using localhost, will work. If for some reason you got problems, try adding an entry on your hosts file in order to emulate your domain locally. But here I dont need that, just works out of the box.
Best
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Robson Dantas
@robsondantas