In my experience, I made a deposit on ladder 16 and the one listed in the reload column will end on the 21st, why only stop there, if only it runs for 7 days instead of 40 days, we'll see for sure tomorrow
No need to worry about it, AFAIK longest activated reload is 7days so perhaps it will be renewed after the 7th day.
So if the offer is 40 days then I assume that your first reload is for 5 days only then you will get another 5 days reload started from 22nd.
It means that there will be another 7 renewed reload during the promotion, so in total you'll get 8x reload @5days each = 40days.
In case there it will not be renewed or if you get it till 21st only then for sure you need to contact bitedge as the one who offer it in a collaboration with Stake.