In THERM 7.6.01, when I load a new material library (such as the one that comes with the installation, called Material-Arch.lib), close the program and restart it, that library is still shown as the Material Library, so it appears the program is saving whatever file you load.
![](https://lh3.googleusercontent.com/-_9e_SXQhkoc/WphwxrqTWgI/AAAAAAAAB-I/RNpRLJlxc1o8bhxgMSM7LVOWgwAod6ClACLcBGAs/s1600/LoadMaterialLib.png)