You can deactivate your Adobe apps if you want, before updating your OS. The way to do this is via the Help menu in the application(s); Help / Deactivate for older apps and Help / Sign Out for CC apps. You haven't said what version of PS you have.
To reactivate after the OS update, if you're on CC you merely log back into the CC app.
To reactivate after the OS update, if you're not on CC, then you need to reenter the serial number(s) and if you don't know it/them, then don't deactivate.