The page says "you can pick a plan later" and that users can "upgrade", which implies to me that people opt into and manually control the pricing plan they want

The page says "you can pick a plan later" and that users can "upgrade", which implies to me that people opt into and manually control the pricing plan they want. But what they have actually behaves more like usage tiers in reality. It also says that staff are considered active if they've used the product within the last 30 days. How could the OP get usage back below the threshold with only 7 days notice?