ProTracker Tennis.

ProTracker Tennis captures information on your players' matches - to identify areas for improvement, strengths to exploit, or to spot opponent's weaknesses. ProTracker Tennis uses innovative graphical techniques making it very powerful but also very easy to use. The best way to learn about the App is download and install it, then use the free trial to track three games and to analyse the two example matches that are included.

Free Trial
Up to three games in a match can be tracked and analysed without a Subscription or Match Credit. Additionally, two example matches are supplied that can be analysed.

Subscription
A Subscription to ProTracker Tennis allows an unlimited number of matches to be tracked and analysed. The subscription is checked before each match is started or loaded - this requires on-line access. Subscriptions will automatically renew unless canceled within 24-hours before the end of the current period - you can cancel anytime with your Apple ID account settings.  

Match Credits
Each Match Credit allows one match to be tracked and analysed. Match Credits can be purchased in advance of their use - they can be used when off-line.

Terms of Use: https://www.apple.com/legal/internet-services/itunes/dev/stdeula/ 
Privacy Policy: http://www.protrackertennis.com/downloads/ProTrackerTennisPrivacyPolicy.pdf