You can upgrade or downgrade your Cocolyze account at anytime and all changes take effect immediately.
When you wish to upgrade your account you will be able to increase the number of tracked keywords and the stored data history period. If you upgrade mid-way through your current subscription, you will be provided a pro-rated refund for your previous subscription and charged for a new one.
If you decide to downgrade your account, no refund is issued for the month in question. The new price will take effect the following month.
To upgrade or downgrade your account go to Account > Billing > Subscription.