I'm assuming that you're talking about your apps updating as actual phone updates do not happen frequently.
You do not have to update apps, but it is advisable to do so as the updates often bring you a better in-app experience. Just make sure that you're set to update your apps over WiFi only to minimize your data usage. You can also turn off auto-update and update your apps manually at your own convenience.
If you need specific information on how to do this with your phone, please provide us with the exact make AND model of your phone.