More info on Portuguese pillbox (Braganza)?

Hello,

I recently bought this pillbox, it seems to be silver-plated. It has no hallmarks, but there is a very small ‘Portugal’ stamp on the side of the lid. I was told that the crown of the lid is that of the royal house of Braganza.
Can anyone tell me more about the age of this pillbox, and why it was produced (commemorative gift or something)?

Thanks,
Natascha, The Netherlands