Look at it this way.
Without the buff the only way to get extra Lab runs is to upgrade your VIP level and therefore you have to buy Gems to get it. Once you do that it still cost Stamina and Gems for each timer that you take an extra Lab run.
With the buff you get an extra Lab run without having to upgrade your VIP level and therefore do not have to buy Gems to get it. Once you do that it still cost Stamina and Gems for each timer that you take an extra Lab run.
So you are in fact getting the extra Lab run for free (do not have to buy Gems to upgrade VIP level). Using the extra Lab run is still not free.
I see nothing wrong with the wording. It is the interpretation that most people give it that is wrong.



