Watcher requires a minimum elasticsearch version of 1.5.0. It looks like you are running an earlier version. You should upgrade elasticsearch if you can. If you need to run watcher against an earlier version you can install it on a separate cluster and use the http input to search the older versioned cluster. See https://www.elastic.co/guide/en/watcher/current/anatomy-input.html#anatomy-input-http
The error message indicates that the license plugin is missing.
You can install the license plugin by executing the following command:
bin/plugin -i elasticsearch/license/latest
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