Summary

For Live Site,

1. Log-in to your Chargebee Live Site

2. Click on the ”...”  near your account name to the bottom left corner of the web interface

3. Click on the block that contains your profile as displayed below
   
   

4. You will be directed to the My Account page of Chargebee.

5. Click Manage Account to update your billing/account/payment information 

6. Click Upgrade to move to a higher plan
   
   

For Test Site,

1. Login to your Chargebee Test Site

2. Follow the steps (2-5) as stated above

3. Click Choose Plan when you are done using the free trial and wish to upgrade.