If you already have purchased the old Business Calendar Pro, you just have to keep it installed on your device to activate all the pro features of Business Calendar 2. Unfortunately we have no opportunity to automatically check if you are a pro user of BC 1. We can only check if the old BC Pro app currently is installed on your device. Additionally we offer an upgrade for BC 2 to use the pro features without having the old app installed to a massively reduced price (please uninstall the old app AFTER purchasing the upgrade for BC 2 to make sure you get the just mentioned reduced price).
If you don't own the old BC Pro you simply can activate the pro features of Business Calendar 2 within the app using in-app payment. You also can buy so called upgrade packages that only contain certain features and are available to lower prices. To activate the pro features you only have to pay once.