Server update error

I tried updating the php version and got a message from “Your plataform does not support PHP 7”

I tried to update the server, but I’m having this error when I run the apt-get update command

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

W: Some index files failed to download. They have been ignored, or old ones used instead.