You can do it with your bank account app. When you notice 1/3rd of your salary has been deducted, you know her period hasn't come.I have found it useful to track the periods of the women I'm currently dealing with. Does anyone know if there is a app that can track multiple periods?
If you want to talk, talk to your friends. If you want a girl to like you, listen to her, ask questions, and act like you are on the edge of your seat.
Quote taken from The SoSuave Guide to Women and Dating, which you can read for FREE.