?
We don't have a formal EoL policy, but as long as you're current on support (which, just checked, you guys are), we'll do our best to provide support for whatever version you are on. Of course, please understand that, a lot of times, the answer may just be "upgrade to a new version", and we most likely will be unable to provide a hotfix.
I suggest you upgrade to v4.6 (we can provide assistance in this as well), and then schedule a routine upgrade/maintenance window (monthly, bi-monthly, etc) so that you can try to keep current. We put a lot of effort into making sure everything is backwards-compatible, and in the event something breaks, you can rollback... or we have the capability to ship a new release within hours.