Can I get a refund for any unused portion?

fit52 is free to download. Ongoing use requires an active subscription, available on a monthly, quarterly or annual basis.

Customers who choose a subscription are eligible for a free 14-day trial period.  Payment will be charged to your credit card through your device's application store account at confirmation of purchase. Subscription renews automatically unless cancelled at least 24 hours prior to the end of the subscription period. There is no increase in price when renewing. Subscriptions can be managed and/or have auto-renewal turned off in Account Settings in your device's application store after purchase.

No partial refunds for unused portions will be given.

Here is Apple's comprehensive guide on how to obtain a refund: LINK TO APPLE

Here is Google Play's comprehensive guide on how to obtain a refund: LINK TO GOOGLE PLAY