One of its main features is the encapsulation of The GNU Multiple Precision Arithmetic Library (GMP) and so providing a simple object to be used representing monetary values in the form of rational numbers. All the mathematical details are hidden inside the AlkValue object.
Why is it version 7.0 while the previous stable version was 5.0? Version 5.0 was solely available for Qt4 and a version 6.0 was started to support Qt5 based development. The problem was, that they were not installable side-by-side because they used the same filename for the library.
The main change for version 7.0 is in fact the capability to install both versions on a single system in parallel. As usual, a few bug-fixes also found their way into the new released version which is available as source code on KDE servers.