How can I make my main actor "store" the power pellets he collides with?

How can I make my main actor "store" the power pellets he collides with?

I have some power pellets working already....when the actor collides with them, they cause him to immediately speed up in the direction he's going.
But instead of using the pellets immediately, I'd like to store them in some sort of onscreen box so the user can activate them via keystroke. (Like a reserve fuel booster kind of thing.)

And I have no idea how to do this. Any advice?

A counter for stored pellets, probably Game attribute.
An inactive (turn off all physics/interaction) actor for the box, with one-frame animations for each state of pellet-volume or however you wish to represent them.
Increase/decrease pellet count causes corresponding change in box-actor.

thanks for the feedback. I'm researching the counter setup now.