You can create more API keys and arbitrarily use all of them. His good way, like Im, also using it without any problems and never received quotas, exceeded the problem. You need to create a separate project for each API. in php you can use it like
$api = array("API key # 1", "API key # 2" ,"API key # 3"); $rand_keys = array_rand($api, 1); $usage = $api[$rand_keys];
A new key will be used for each request. The best way to avoid downtime.
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