You can invest your tokens by tripling your offline income when you enter back the game.
If you tap on the star icon (lower-right corner of your playing screen), you will see collectible figures that provide permanent epic upgrades. You could unlock them with vending-machines that should have paid by tokens. 
Toy-Vending machines provide your parks with permanent boosters and upgrades. You will be able to earn special figurines that will increase specific features in your game. Some of them will appear in your theme park! Others are passive multipliers.