Children of the Dust

Humanity has been fighting a brutal, centuries-long war against a hive-minded alien race, with entire generations born and raised as soldiers on the front lines. The story follows a war-hardened officer who leads a team of genetically engineered "Dustborn"-child-soldiers born from harvested DNA of fallen heroes and trained for battlefield excellence but with short lifespans due to built-in genetic limits.
When the officer and his squad are ambushed and stranded on an alien planet, he discovers that the Dustborn have started developing memories of the people they were cloned from-memories that aren't supposed to be there. Realizing that the Dustborn may be developing independent souls or consciousness, he's torn between using them to survive and trying to save them from the ticking clock of their lifespans.