Premium licence activation and multiple Google accounts on the device

Use the following workaround to install the app with an active premium licence and with multipe Google accounts on the device:
1) Uninstall GymRun, if you have a data backup (and a second backup)

2) Using a desktop browser on a computer, open this Play Store link and log in using the same account you used to purchase the license and which is set up on the smartphone

3) Click on “Install” button on the web page then wait the install process to finish on your smartphone device
4) After the installation check if the app recognized your license if it doesn’t a reboot of the phone could be necessary