Hi,
The process is the same as for all cloud options. For example, you get 15 GB free on Google Drive but when you buy 100 GB storage you get 100 GB only, not 100 + 15 = 115 GB. When the subscription ends the storage lapses back to the initial size.
When I go to that link, I get this message: "In order to purchase a storage plan, you need to access this page by clicking on the increase storage button on your ecloud.global account ", but where is that buttom? I have looked everywhere in the settings and more that I can think off.