Correct. Depending on how old your version is, there is a good chance that your old version isn't compatible with the latest OS.  So what you have to understand is that while the version that you have _was_ current back in 2010 or 2012 or whenever, the Mac OS has updated itself numerous times since then. Developers (not just Mariner, every Mac developer) were not developing their software in 2010 to work with a 2018/2019 operating system. For that matter, they weren't developing it for a 2013 operating system. The bottom line is that it really is unrealistic to think your 2010 version could work with a 2018 OS (for MacGourmet Deluxe or any app). 

Whether it's a Mariner title or any other title, it really makes sense to keep the most current version installed on your Mac.