You make sure your updates are backwards compatible as far as field names. That would be a good start. It’s ridiculous that you allowed something like that to happen. We’re running a business and your updates put that business at a standstill because the plugins no longer worked together. How much money did that really cost me – besides having to pay $249 for an “updated” plugin of what I already had? How much revenue did I lose because clients saw an error and decided not to book?
I had already paid for these things. But you rip people off with “subscriptions” that expire, and then refuse to help them when YOU break them. That’s not good business.