If you are using Roamless pay-as-you-go (FLEX) credits:
Since your pay-as-you-go (FLEX) credits are consumed per MB of usage and have no expiration, there is no need to 'pause' anything
You can simply turn off your Roamless eSIM on your device settings when you don't need to use it, and turn it back on (and select it for data connectivity again) when you want to get connected
If you have a Roamless Data Plan (FIX Plan)
Once your data plan has been activated (after the first KB of usage), you cannot 'pause' it
You have 30-days from activation to use your data plan before it expires
If you have not activated your data plan yet (i.e., no data usage on the plan), it stays valid in your account, ready for use for 12 months after purchase
If you are interested in being able to "pause" your data usage, Roamless pay-as-you-go (FLEX) is likely the right fit for you.