This question already has an answer here:
Let me get one thing straight first. I am not saying that fundamental constants like the speed of light don't have the value that we know they have today. What I am asking is whether the value of a constant could change with time. For example, we measure today that the speed of light is almost $300000000\,m/s$, but this measurement was made over the last century. But what if a long time ago (billions of years ago) that constant had a different value?
So, it's always the limit of how fast something can move, but that limit slowly changes with time.
To conclude,i am asking if there is any kind of evidence that any of the fundamental constants like the speed of light remain constant in time or if we just took that for granted.