You can upgrade to a larger web hosting product at any time.
For an upgrade navigate to [Web Hosting] → [Product Settings] in your control panel. Choose the product you want to upgrade to and click on [CHANGE].
You can always downgrade after the runtime of your current product.
In order to downgrade the product by the end of the runtime, navigate to [Web Hosting] → [Product Settings]. Choose the product you want to downgrade to and click on [CHANGE].