Does the app reuse addresses?

Everytime a single order is created, a new ethereum address is derived from your wallet. In this case there won't be any address reuse.

In the case of a recurring order however each payout will always be sent to the same address generated during the order creation. You can share your entire wallet (XPUB) with Pocket, so that each payout occurs to a new unused ethereum address. Just enable the option "Advanced buy options" in the advanced settings and you'll be able to import XPUBs.