The answer is YES.
UPGRADE YOUR PLAN
For instance, if you are on the Lite plan right now, you can always upgrade to the Enterprise plan.
You can do this via the dashboard if you've already purchased a plan or writing an email to firstname.lastname@example.org
DOWNGRADE YOUR PLAN
To downgrade your plan, write an email to email@example.com
How is the price adjusted?
The price is adjusted on a prorated basis automatically.