Repo Key Expired Error for EasyEngine on debian 8

W: An error occurred during the signature verification. The repository is not updated and the previous index files will be used. GPG error: Release: The following signatures were invalid: KEYEXPIRED 1501595774

W: Failed to fetch

How can I download the correct key?

Just use the command :

sudo apt-key adv --keyserver --recv 3050AC3CD2AE6F03