>>267677614
Battery memory does not affect Lithium Ion batteries.

Lithium Ion batteries are rated for a number of "charge cycles" typically anywhere between 500 and 1500 Charge cycles before they will fall to 80% of their original capacity. A charge cycle is measured as a complete discharge -> followed by a complete charge. 
If you use 50% of the power then charge it back to full, that counts as half a charge cycle.