If you don't have an ECMWF account, please self register at https://api.ecmwf.int/v1/key ( click login and then register ) and then follow ONE of the steps below.
You can also try visiting https://api.ecmwf.int/v1/key/ to retrieve your credentials.
Note that the key expires in 1 year. You will receive an email to the registered email address 1 month before the expiration date with the renewal instructions.