Freshchat allows you to upgrade and downgrade your plan at point of time.
Here is how you can upgrade or downgrade your plan.
Login to Freshchat as an Owner.
Go to Settings -> Account -> Plans. You can find your current plan along with the number of users you have added. You will also find details about your next renewal date, along with your payment details.
Click Choose a different plan and you can choose from the different plans listed.
Click the Choose Plan button under your plan of choice. Hit Confirm once you are done.