linear actuator internal resistors
2.5A is the load at 100% of rated force- during starting and if you overload it, it will draw more than that. Note that the duty cycle is only 25% at full load. If you run it for 30 seconds, say, you have to let it rest for 90 seconds before operating it again. 

The current drawn (after initial start-up) will be roughly proportional to the load. So for a lighter load, it will draw less current (though never quite zero because of friction and other losses), and it will draw the maximum when stalled (not a good idea). In a sense then you do control the maximum current to the extent you limit the force the actuator must produce. Since it has limits switches built-in, you don't need to worry about stalling it at the end positions.