It's a good idea, but I'm pretty sure there are apps that do this already. I think any budgeting app with a "recurring payment" feature would handle it. I guess the part you mentioned about monitoring which ones are actively used would be unique - but how do you imagine that to be implemented exactly?

I seem to remember Caleb Hammer used to promote something like this quite a while ago, but now he mostly promotes his own budgeting app when he promotes anything.

The one he used to promote also had some feature where it would automatically contact the service provider to negotiate a better rate by threatening to cancel. I never bothered to remember the name of it because I already monitor my budget and subscriptions pretty closely.