Hello, is it just the same song that stops?
We have had no reports of this happening in general on either iOS devices or Mac.
Please make sure you have up to date versions of iReal Pro from the Mac App Store and iOS app stores.
You can always do a backup and download a fresh copy from the App Store (use the same Apple account as you used to purchase it, so the download is free), import your songs again from the backup file then test again.
If you have further problems please contact us directly using the Help page.