You have two sets of two keys: one set for Test mode and one for Live mode.

The set of keys you use determines whether actual money will be transferred or not. In other words, you should use your Live keys only on your production server.

Test mode keys: For testing purposes only, no live transactions take place.
Live mode keys: For live transactions. Payments are processed by card networks or payment providers.

Whenever you roll your keys or change your passwords you will get an email notification. Please check your Omise registered email frequently.

If you believe your secret key has been compromised, go to your account dashboard and roll your key immediately.

For more detailed information, head to this documentation page.