Using Quicken 2007 0n a Mac running Sierra 10.12.6

@Janell As John notes, you can upgrade one step with your operating system, from Sierra to High Sierra — but if you only plan to use the computer for Quicken, offline, and don't need to do web browsing or email, it may not matter, 

I'd like to caution you about two issues with planning to continue to use Quicken 2007 indefinitely into the future:

(1) Quicken 2007 is old software, as you know, and it uses a very old database which is known to have occasional fits of data corruption. I once lost a small chunk of data and had another chunk of transactions inexplicably transported in time to a different year, which I didn't discover until about 6 months after it happened (determined by going back through old backups). Fortunately it wasn't critical data for me, but other longtime Quicken 2007 users have experienced data stability issues at times, so it's worth keeping that in mind as you continue to use software which hasn't been update in a decade and whose roots go back much farther. It's also worth keeping in mind that many computers or their hard drives eventually give out, and if you're using a computer which is already about a decade old, you should consider yourself  on borrowed time going forward. That said, it's quite possible that you could continue to use Quicken 2007 for another decade if your computer holds up and the Quicken database doesn't have one of its hiccups. 

(2) For the past seven and a half years, the modern version of Quicken Mac has been able to import Quicken 2007 data files for those who want to move forward with Quicken. Currently, this relies on code in the Quicken application as well as Quicken servers which perform a critical part of the data migration. At some point in the future — it could be next year, or it could be 5 or 10 years from now — Quicken is likely to retire that conversion server and code, leaving no way to migrate data from Quicken 2007 to the current Quicken Mac. Hopefully, they will provide plenty of advance warning so the small number of people who are continuing to use Quicken 2007 will have time to get an appropriate computer environment to migrate their data if they wish to, but we have no way of knowing when or how they will cut off conversions from Quicken 2007. Quicken has removed nearly all mentioned of the 2007 Mac version from their website, and it's not clear if they have a way to reach out via email to people still using Quicken 2007 when the time comes. So it's just worth staying aware that there may not always be the path to upgrading your data which exists now.

My intention here isn't to scare you, or to push you to upgrade your computer and purchase a new version of Quicken! It's just to make you aware of the risk factors involved in planning to continue use of an old computer with this piece of old software. Please make sure you do rigorous backups, not just of your Quicken data but of everything on your Mac to one or more external locations in case your Mac or hard drive suddenly die. (Time Machine is a great tool for this, as are disk utilities like SuperDuper! and CCC, which can make while disk backups to an external disk drive, and/or Cloud backup services like iDrive or Backblaze, at least as long as they continue to support Macs running Sierra.)