The Deployment Key will allow you to create an ssh-key to deploy your web application using GitHub or Bitbucket. Every system user can only have one deployment key and can be used again except in GitHub.
Please note that when you generate a new key, the old key will be invalid and your GIT Webhook won't be working.
You can generate deployment keys 10 times a minute. After a minute has passed, you can generate another one. This is to ensure that you are not spamming our server since SSH Key generation is resource-intensive task.