Rocket Racoon: If the last charge counter is removed from one of Rocket Raccoon’s upgrades, is that upgrade discarded?

No. When Rocket Raccoon’s upgrades run out of charge counters, they remain in play. This is because Rocket Raccoon’s upgrades do not have the “uses” keyword, and that keyword itself is what discards cards that run out of counters.

-Galaxy’s Most Wanted rulebook