Whats the best way to make a 2x exp gamepass?

I've seen people do Changed, or just change it whenever they reward exp in every script or whatever they give exp with. I want an efficient way. Not asking for scripts. Just drop some ideas or a solution that'll help me.

You could check whether a Player owns the GamePass once they join and cache the output to a BoolValue within the Player. This value could then be updated if they purchase the pass in-game and can quickly be checked when you need to award exp.