Instance variables/internal state for Blueprint Function Nodes within Component

I am building a series of Blueprint Function Nodes exposed through an Actor Component.

One of the functions is to compute a running average, and therefore I would like the “RunningAverageNode” to hold a buffer of *previously computed *averages.

TArray -> RunningAverageNode (holding array of last N averages) -> Average of last N Averages.

How can I do this–have a blueprint function maintain an internal state/variable? I don’t want this variable to be component-wide because I want it to be scoped to the individual blueprint node.