All upgrayedds are handled in-app.
If you are in the Free Trial or Standard tier and wish to upgrade you can use the following slash commands.
/eletype upgrade
If you are in the free trail you will see this:
If you are in the Standard Tier you will see this:
You can also upgrade from the Account command.
/eletype account
Need help with additional slash commands? Check out this article: Eletype Slack Slash Commands