When moving from a numbered release (E.G. v18 to v19, v19 to v20, etc.), note that certain 3rd party plugins like AreaList Pro or CalendarSet will have it's own licenses linked to your 4D license. If you intend on upgrading your 4D version which will use a new 4D license, make sure you consult the plugin developer for a new plugin license otherwise the plugin may only work for a limited amount of time.