MacBook Pro 10.13.6 Needs Parallels 17

I was recently forced to update my MacBook Pro to Mac OS 10.13.6 in order to retain DropBox support. Upon doing so my older install of Parallels will no longer run VMs. In looking into this further it seems the latest version, 18, does not support Mac OS 10.13.6. This MacBook Pro cannot run a newer version of Mac OS. How can I get a license for an older Parallels version? Parallels Version 13 works well on my other computer with 10.13.6. Parallels Version 17 is apparently the last version that will work with this OS.

Thank you for any information.

 

Just for anyone else looking older versions are available online. Not forever, so hop on it if you need to. No assistance here. I suppose I'm not surprised. They never realize those big business owners who are willing to spend big money to continue developing with older tools still have these questions. Kudos to the support staff.