I want add service expiry date

Dear Team,

Greeting From Zafar!!!

I want to add option in invoice service expiry date for 1month 3month,6month, and 12month. and date will take automatically fill in provided space.

you can add custom field with date option. but you need to set the expire date manually

One addition to what @abdulbari wrote. Once the custom field is defined, you can set a default entry under Form Defaults for your most common option. See https://www.manager.io/guides/14059.