You can always open a model file in two newer versions. This means that if you have for example a model file created in version 14 then you are able to open it in FEM-Design version 15 and 16. And to be able to open it in the newest version then you can do according to the method below:
Created model file in v.14 ====> Open in v.16 and save the file (now the model file is saved as v.16) ====> Open in v.18 and save ====> Open in v. 20 and save ====> Open in v. 22 and save ====> Etc.
You can always see which version the model file is saved as before you open it as below:
From the application StruSoft Installer on your computer you can install the different versions of FEM-Design.