Can I switch plans at any time?
Upgrades take effect immediately and are prorated with any remaining credit on existing membership. Downgrades, cancellations or changes from annual to monthly take effect at renewal.
For example, let's say you get the Standard plan for $300 today. 3 months later, you want to upgrade to Premium. Since you've used only 25% of your Standard you get a credit of $225. You'd pay $195 ($420 - 225) to purchase 12-months of Premium.