You can subscribe to Xmind Pro from App Store.
1) Launch Xmind for iOS,
2) Go to Settings > Upgrade to Xmind Pro，
3) Select the subscription you want to buy，
4) Sign in with your Xmind account,
5) Enter purchasing page to pay for the subscription.
* Subscriptions purchased from App Store will be auto-renewed. You can cancel the auto-renewal anytime. If you need to get a refund, please contact Apple Support.
How to cancel the auto-renewal?
1. Launch the Settings APP.
2. Tap iTunes & App Store.
3. Tap on your Apple ID.
4. Tap View Apple ID when the pop-up window appears.
5. Enter your Apple ID password or fingerprint ID when prompted.
6. Tap Subscriptions.
7. Tap the Subscription you want to cancel.
How to get a refund?
1. Launch Mail from your Home screen.
2. Search for "Your receipt from Apple" if it's not immediately visible.
3. Tap on the receipt for the purchase your want refunded. ...
4. Tap Report a Problem next to the purchase you want to report. ...
5. Enter your Apple ID and password when prompted.
If you fail to get a refund following these steps, we suggest that you can contact Apple's customer service.