I am old enough that I started with Purify and I used Valgrind starting from the version 1.0, because Purify was commercial and Solaris only. It saved my behind multiple multiple times.
Purify was an amazing tool. I recently noticed that one of my libraries (libffi) still has an --enable-purify configure option, although it probably hasn't been exercised in.. 20 years? A Purify patent prevented work-alikes for many years, but valgrind eventually emerged as a more-than-worthy successor.
Fun fact: the creator of Purify went on to found Netflix and is still their CEO.
That tool saved me tons of time tracking down bugs. It also taught me to be a better C/C++ programmer. Run time sanitizers like Purify/Valgrind/Boundchecker do not tolerate poor C code. What is kind of cool is you can find whole classes of bugs in your code. Because as devs we get something working once we tend to copy and paste that pattern everywhere. So find a bug in one place you will probably find it a few dozen other places in your codebase.
I used Purify 8 years ago. On Windows. I don't remember the specifics but the company kept a few XP machines around just so they could continue using Purify.
Fun fact: the creator of Purify went on to found Netflix and is still their CEO.