Subscription & Payment - in app or via website?

Just wondering what folks experiences and advice are about whether there is any advantage to implementing subscription and payment-related functionality (choosing plan, provisioning subscription in Stripe or similar, setting up credit card) in app versus on the app's landing page / website.

With Wordpress + WooCommerce + Stripe, or similar, it's pretty straight forward to do all of that on the landing page / website for your app. That even seems convenient...

Or I could build UI and back-end code (i.e., integration with Stripe API) to do all of that as part of my app. Just not sure why I'd want to invest time in that.

Thoughts? Thank you!