If you follow the instructions for correct use and cleaning and don’t damage it, your MamiCup will last many years, up to 10.
However, if the material starts to crack, it’s time to change your cup.
Other variations you may notice may have to do with the material or shape.
Discoloration or staining should not worry you: this is normal after many menstrual cycles, and the cup’s functionality is not affected in any way.