1. Sign in to your Zapendo account.
2. Go to "Billing."
3. Click on "Plan" and select the plan to which you would like to upgrade.
4. Click on "Update Plan."
5. Sign out and sign back in to make sure the change has happened.

You can change anything else in your billing section as well. After you make the changes, don't forget to click on "Update Plan" for changes to take effect. Downgrading your plan works the same way, just in reverse.