Monster Tools currently support Stripe and PayPal as payment gateway. You can either enable one of them or both at the same time. To enable Stripe go to Settings > Payment Gateways and you will see two tabs Stripe and PayPal.
How to Enable Stripe Payments
Enabling gateway is simple go to Settings > Payment Gateways > Stripe and click the stripe switch. After enabling the Stripe Key and Stripe Secret options will appear.
Register your stripe app in Live Mode for production and Test Mode for testing. Follow the instructions on how to setup Stripe App for app setup details. Paste your App key and Secret and click "Save Settings" button on the setting page.
How to Enable PayPal Payments
Similar to Stripe you can go to Settings > Payment Gateways > PayPal and click the PayPal switch to accept payments using PayPal. Read the instructions on how to setup PayPal app for details.
After creating your PayPal app you need to copy the App ID, Client ID and Client Secret on the rewards settings page and click "Save Settings" button.