Your purchased key is meant to remain valid even if you upgrade to newer versions.
You can use the free version to scan and see if files are present; if IsoBuster cannot see them, the Pro version won't necessarily find them either. Isobuster 3 8 key
Handles damaged CD/DVD/BR, HDDs, SSDs, and USB sticks. Your purchased key is meant to remain valid
Licenses are generally valid for future versions, and registration should be done in the Help menu. Important Tips for Users Licenses are generally valid for future versions, and
IsoBuster 3.8, released in June 2016, is a robust version for recovering data from damaged optical media (CD/DVD/BD) and various image files. The professional/paid version is highly recommended for full data extraction capabilities, as the free version may not unlock advanced recovery options needed for severe, non-finalized, or corrupt discs.
Supports scanning for missing files and folders (using "Find missing files and folders" via right-click).
As noted by developers, using "not so legal" keys found online may result in the software disabling registration functionality.