The ‘Pro upgrade’ in-app-purchase for RaceChrono for Android will activate immediately after the purchase. The application name (and icon) will remain as RaceChrono, and will not change to RaceChrono Pro, but the app features will upgrade 100% to ones of RaceChrono Pro. There’s no difference in features. The upgrade is activated, if the ‘Pro upgrade’ item in the upgrade screen says ‘Bought!’.
That said, there’s couple of things to consider.
1) When you change phones, or want to install on your secondary device, make sure you install the RaceChrono app, not the RaceChrono Pro app. It will upgrade automatically, as it did for the first time.
2) You need to have same Play Store account on all of the devices where you want to use RaceChrono on.
3) If you just made the purchase on one phone, and do not get the upgrade immediately on your second device, you can reboot the second device and open the Play Store app. This is to update the inventory of purchased items. Also open (and re-open if needed) the Upgrade screen in RaceChrono to update the inventory. Your purchase should appear there eventually, and then your purchased items will say “Bought” on the button next to it.
4) If you have previously successfully activated Pro purchase and it has since become inactive, and cannot be activated by just rebooting, it maybe because of invalid state within Play Store app. You can do the following: 4.1) Clear all Play Store app data (not just the cache) from Android settings > Applications > Google Play Store > Storage > Clear data. Notice do not clear RaceChrono data, it will delete your sessions! 4.2) Reboot your phone 4.3) Open the Play Store app again, so that it restores all data and reloads the store 4.4) Open RaceChrono and go to upgrades screen 4.5) If Pro upgrade not yet activated, go back and repeat from 4.4 couple of times.