You can manage your subscription using the Chargebee self-service portal. Note that it is a different system than InfraNodus itself, so you will need to log in separately in order to be able to access it.
Once you log in, you will be able to upgrade or downgrade your subscription in the self-service portal.
Step 1: Go to the Settings if you are logged in or open the Login page and click "manage your subscription.
Step 2: Open the self-service portal to manage your subscription via Chargebee and then enter your email.
Step 3: You will receive an email with a one-time password. Enter it to log in.
Step 4: Click Manage Subscription. You will then see several subscription options which allow you to upgrade or downgrade your subscription.