Hi Matt,
Thanks for reaching out!
The current version for Pro is 4.4.17, and the current version of The Events Calendar is 4.5.13. These two versions should be compatible with each other. The current version numbers won’t necessarily be the same between our plugins, but you can always see the most recent versions by going to My Account > Downloads.
It looks like you’re running Pro at 4.4.17 (awesome!), but you said your site breaks when you update the free version to 4.5.13? Could you provide more details on what happens when you update, such as any relevant error messages or screenshots? If you don’t currently have a testing environment, the WP Staging plugin will let you create a quick copy of your live site that you can use for testing.
In your testing environment, can you try deactivating all other plugins besides TEC (free version) and Pro and switching to a default theme (such as Twenty Seventeen) and see if you are then able to run both Pro 4.4.17 and TEC 4.5.13? If so, then there is likely a conflict between the current version of TEC and your theme or another plugin. You can verify this by enabling them one at a time until you are able to recreate the issue (your site breaking) that you are running into.
When testing, please make sure to have WP_DEBUG enabled and copy/paste any errors that appear into your reply here. Let me know what you find!
Thanks,
Jennifer