reDraw (iPad whiteboard/presentation app) continues active development with new features planned. If you have an iPad Pro with an Apple Pencil and teach in a classroom with a projector, I think you'll find it a great app.
Attendance2 continues to be supported. I spent part of my holiday break and part of mid-semester break updating it to work with the new Dropbox API. Dropbox is turning off the old API in June 2017 so versions prior to 5.0 of Attendance2 (in beta testing now and I plan to release in April 2017) will no longer work with Dropbox when Dropbox turns off the old API. You will need to update to version 5.0 of Attendance2. The new Dropbox API requires iOS 8 so version 5.0 of Attendance2 will require iOS 8 or newer. I know as of 2016 there were at least a handful of people using Attendance2 on iOS 7. Version 4.x of Attendance2 should continue to work on those devices other than Dropbox will not work. You will have to use the options to backup via Email and load .adz or .csv files by emailing them to yourself and tapping on the attachments in the Mail application and choosing to open in Attendance2.
Version 5.0 of Attendance2 includes a few new features and there are still a few features I may add in future versions.
The original Attendance app will no longer work with a future version of iOS (likely iOS 11, but possibly with a point release of iOS 10). Apple has indicate they will no longer support 32 bit apps and updating the original Attendance app (originally written for iOS 2 and supported through iOS 7) would require a complete rewrite of most of it. The App Store page has discouraged people from buying it since I released Attendance2 when iOS 5 was current. It will be removed from the store soon.
My Mac GradeA app was released with Mac 10.6. It cannot be updated with any new features in the Mac App Store as they require new feature updates to be sandboxed. The functionality of GradeA cannot meet Apple's sandboxing requirements (the emailing of grades features are incompatible with sandboxing). Apple has indicated they will allow bug updates (and I have released a bug update or two) so I hope to continue to make it run on future versions of macOS.
TL;DR: the original Attendance app will stop working. Attendance2 version 5.0 will require iOS 8 or higher and if you are using Dropbox, you must update to that version by June 2017.