A Grandfathered plan is a plan that is no longer available to purchase - but remains available to customers that are already on that plan.
When new web hosting plans are released we do not force customers to change. Instead our current plans are "Grandfathered" so that customers can continue using the resources at the price they signed up for. There is no need to upgrade if their existing plan suits their needs.
If a customer moves to a current plan then it is not possible to go back to the Grandfathered plan. Grandfathered plans are only valid whilst the account remains active.