Free version vs Pro

Does the Pro version allowing altering of .STL or .STEP files? Looking to adjust chamfer/fillet edges on existing .STL and .STEP. Just wondering before I purchase.

On .STEP, yes, on .STL, no, as that format doesn’t have edges to begin with. You can still use boolean operations on STL though, so it might be possible to what you want to do, it’s just more complicated and model dependent.

You can import these formats in the Free version and try if they work for you.