What is stamina?
The counter for your stamina indicates the time that is left until a character is too tired to gain experience while hunting. Characters can hunt for up to 42 hours before they no longer gain experience points. In the first two hours, so up to hour 40, premium players gain 50% more experience points for every monster killed. During the final 14 hours defeated creatures will only yield half the experience. Moreover, if the character that has dealt the most damage to a monster has only 14 or less hours of stamina left, the defeated monster will not contain any loot.
Stamina regenerates while characters are logged out. For every 3 minutes you are logged off, your character will gain 1 minute added to its stamina up to hour 40. For the last two hours, your character needs to be logged off for 10 minutes to regain 1 minute of its stamina. Please note, however, that stamina only starts to regenerate after you have been logged off for 10 minutes.