This option adds or changes the API key!
Usage:
ddns -a AIzaSyDaGmWKa4JsXZ-HjGw7ISLn_3namBGewQe
or
ddns --api AIzaSyDaGmWKa4JsXZ-HjGw7ISLn_3namBGewQe
If there is no API key present it creates/ stores the key in the local db. If there is an API key presents it updates/rewrites the API key in the db and uses this key from now on.