A game will end in a draw according to the FIDE Laws of chess (6.9) "if the position is such that the opponent cannot checkmate the player’s king by any possible series of legal moves." So a player loses the game if her clock runs out and mate is possible.
The chess24 Playzone ignores this rule, as we think it should not apply to modern internet chess. Thus we avoid time battles with material distributions like K+N vs K+N. Instead the result of the game depends on whether there is a forced mate in the position or not.
Example 1 (K+N vs K+P): Objectively this is a draw. The game ends in a draw, although a mate would be theoretically possible.
Example 2 (K+N vs K+P): The player with the white pieces wins as there is a mate in 4.