First off, thank you for purchasing and supporting ScoreCam!

Unfortunately there is no current path to upgrade from a lifetime purchase [PRO version] to a subscription [Live Streaming +PRO]. Apple handles all the financials so there is no way for me to give you a refund directly. However, I would suggest you ask for a refund from Apple and then go ahead and purchase the subscription you want. 

Here is the official support link from Apple on how to get a refund: Request a refund for apps or content that you bought from Apple.