Extending your Dynamics 365 Online Subscription
If you fire up a 30 day trial just to kick the tires or you need a development environment for a temporary time period, it is now a lot easier than before to extend your Dynamics 365 online subscription.
But don’t let it get to this point before you attend to it. If you do then you will have to open a support case, get a call and jump through some hoops to get it renewed.

When you get the following email, login to the portal.office.com interface and start the extension process.

When you login go to the Billing, Subscriptions area. then click on Extend Trial.

Then you get this screen which does require you to provide a credit card. But you won’t get billed until another 30 days go past. At which time you can cancel without incurring any fees.

After providing your credit card info and submitting you get sent to the success page! Don’t ignore the 30 day extension period deadline cause if you do you will get hit with the first monthly bill of $115/user.

Hi,
There is wrong information on this article.
The credit card will never be billed on regarding the trial extension. User never needs to cancel the trial subscription (after using credit card for trial extension) but needs to opt-in for the production use separately (which then generates the bills).
Cheers,
Sauli
That has not been my experience within the UI flow.