example : your first buy was 3 sessions (1year) for 59€. And you received ONE key to let run 3 bots at same time.
Now you need just one more session so everything you need to buy is 1 session for 1 year (or lifetime) so 25€ (or 39€) and you will receive another Key.
First KEY = 3 session = 3bots
Second KEY = 1 session = 1bot
Thats all