Themeforest/envato market question

Hi,
What is the difference between subscription and one time buy of theme? For let’s say one wp theme you have to pay around $60 and you can buy monthly access to all items for $30. As I understand you can download as much as you can in this 30 days and all of the themes and plugins will be activated. So what’s the point of single buys except for lifetime updates? If you stop subscription plugins and themes are still registered/unlocked?

one off = www.themeforest.net

subscription = www.elements.envato.com (there are WP themes but it is NOT access to all of themeforest)

Themeforest = 6 months support and lifetime updates (As long as the theme is available)

Elements = no support and no updates

FYI - you can download as many as you want and you can keep using items which have been used in a project but you have to be subscribed when finishing a project using an item form elements and you cannot stockpile items for when you are no longer subscribed