Can stores using Payflow Pro (with PayPal Express Checkout) use Third-Party Subscription Apps?

[jtyarks]

A store I'm working with is hoping to enable subscriptions, but we're seeing a "Sorry, Shopify says your store is ineligible for subscriptions" error when attempting to enable the Recharge app, and I'm getting conflicting information as to whether or not it's possible to fix this.

The store is using PayPal Payflow Pro for payments, however, the "PayPal Express Checkout" option in the store's payment settings is enabled, which we hoped would satisfy Shopify's Subscription App Eligibility Requirements.

After seeing the error, I asked Recharge and the Shopify Assistant if using this option was enough to comply, but Recharge didn't know and the Assistant gave two different answers: 

Per the Assistant's second response, I'm not certain if Reference Transactions are enabled for this particular account, but I can do so if that would make it work. However, the mismatched responses and documentation make me uncertain if it's even worth the request.

Thanks in advance for any advice or direction.

[Gordon_Chan]

A bit late, but you need to be aware that Payment Pro / Payflow Pro is old PayPal product which are deprecated. Both PayPal and Shopify are going to take this off. PayPal Express Checkout / PayPal Checkout is their modern and standard checkout function which support subscription. Just that it requires a prompt (they call it PayPal in-context checkout window), and either login as PayPal member or checkout as guest for the checkout. And I believe for subscription, it might require PayPal member login so as to charge them subsequently~
Payment Pro / Payflow Pro allows showing card form in Shopify checkout flow, and PayPal handle the card processing. PayPal has Advanced Checkout which allow such thing but it doesn't seems Shopify is upgrading to that integration.