To use your own numverify api key, simply add an entry to your .env file:
NUMVERIFY_KEY=81e071e119d4cd3185c48a66ee8f06b0
It might be best to use one of your own though as I am getting close to the monthly usage cap for the numverify free tier :)
To run the console command (from within the project directory):
php artisan phone-numbers:verify input.csv
there is an example input.csv included in the project directory but any csv file will do.
Generated csv files are saved within the project directory as output-Y-m-d-h-i-uniqeid.csv
It's probably a bit overkill to have a Laravel project for one command - I could have tried Laravel Zero but it is unofficial, or even a Symfony Console app or built it from scratch but I am more experienced with Laravel and genuinely a lot faster at using it.
To run the tests, run vendor/bin/phpunit from the project directory.