You wouldn’t need to renew your license to continue using 2017r3. Builds may not work on the latest macOS, as I’ve seen intermittent FolderItem issues with builds from pre-2020 releases running on Big Sur.
You may have to reach out to firstname.lastname@example.org for this. You have access to IDE versions your license covers on the Download Archives page, but I don’t think you can download an IDE you don’t have a license for to try it out.
On Windows, this answer is much easier.
Windows is very backward compatible, and if Xojo runs, your old licence will work and you can build.
The one-year thing is updates.
On Macs, the same is true, although Apple break OSX for Xojo apps by changing the rules with alarming regularity.
Nonetheless, I would expect Xojo 2017 to work fine even on Monterey (untested)
Although for some apps you need to allow permissions to full drive access in security preferences.
(On iOS, however - and I speak from bitter experience - even though it costs 4 times as much and does a lot less, you will would be lucky to get 18 months worth of useful building time from your licence, due to Xojo’s tight coupling with specific Xcode versions)
The folder item issues disappeared because they switched out the underlying system APIs, but Xojo introduced several other critical issues. It’s a juggling game, and I’m not sure which IDE is the most reliable currently.
Now and then I have a user or 2 who lose access to their Application Support folder. Yesterday, I had a user who had an IOException for the application folder. For Mojave. Then there is the user who suddenly can’t create a file in the temp folder anymore. After thousands of files already have been created.
The temp folder used by 2017r3 / old file system APIs has some weird security attached to it in newer versions of macOS. We see lots of weird issues reading & writing files and also with the Xojo Mutex class which also uses the temp folder.
For FAT32: max number of files in a directory is 65,534 if the filenames are all short (11 chars or less I think)
The use of long file names can significantly reduce the number of available files and subfolders within a folder.