For what it's worth

I bought the Basic version of Business Accountz in early 2011 and had been using it happily for three years when Accountz decided it was time to milk me for more money: my version would no longer be supported and it was time to buy a new version.

Their end-of-life policy isn't explicit, but a look at their Product Lifecycle page showing release dates and current support status shows what they have done in the past. Today (2 November 2015) they are showing that a product that was the newest available just two years ago (Business Accountz 2013) is no longer supported. I wouldn't buy again from them - even if they were only as mean as they are now, I would be looking at a permanent licence that became difficult to use after a matter of a couple of years, and if one of their shareholders needed a yacht, there would be nothing to stop them trying to gouge me for a following version even sooner.

Things are even worse for Business Accountz Basic which only dates from 2010, but for which you will really struggle to find installers if you need to update your PC. The files for version 10.2.1.0 are availabl here  (today at least) - but Accountz really don't seem to want you to find them: there doesn't seem to be any link to that page from elsewhere on their site.

And your woes don't end there. Armed with your reinstalled program, and a file with a "tex" extension, how do you restore it?

Replacing the newly-installed BAK directory with your archived BAK directory seems like a good start, and then try the restore program "BA Restore.exe". But no - that only spots BAK files and not tex files. (Which is a bit scary - at a first glance you fear that all your more recent work has been lost).

How to restore a tex file? Who knows?- Accountz, having moved on from this version, seem to have no interest in helping you (not from their website, anyway). Perhaps a phone call or email will elicit some help, despite their "end of support" decision. Luckily, I found another way ...

In  my case, I had the full installed file structure available from my old hard drive, so on the new PC, I installed the 10.2.1.0 legacy installer (link above) which was more recent than the disk version that I had. Then, without running Business Accountz, I went to that new PC's "Program Files (x86)" folder and renamed the "Business Accountz" folder to "Business Accountz DO NOT USE". I then copied the whole "Business Accountz" folder (programs, data, settings, the lot) from my old drive to my new PC's Program Files (x86) folder.

In due course, I can delete the "Business Accountz DO NOT USE" folder and all will be tidy, but I'll leave it there for a few days in case of complications.

But as far as I can tell, all is working happily.