I have already purchased v3 of SGP but haven’t actually started using it yet (still using2.6). Now I would like to use the Notification system (which is included in the v3 purchase) but I can’t license it in 2.6. Is it possible to make this available in my 2.6 installation?
Yes, once you upgrade your 2.6 license to 3.0 it should be available in 2.6 automatically. If not you may try releasing the license for that machine and re-licensing it.