Are there any apps that you have NO problem throwing money at?

When it comes to IAP, VSCO Cam can have all my money. This seems to be one of the very rare instances where I will spend money on whatever they put out. The other two were Procreate and Paper by FiftyThree. I love those apps so much.

what apps do you use that you've found yourself spending on? keep in mind, I'm not talking about the initial purchase price.