Never tried Stripe’s trial period feature, but I think instead of doing that, you can allow users to try out your product for free, for 7 days.
You could add a date field (subscription expiry) to the Users collection. When a user signs up for the trial, set the expiry date to, say, “Start of today + 7 or 8 days”.
And maybe add another true/false field (“signed up trial?”) and set that to false by default, but when he/she signs up, set that to true.
So the “trial sign up” button or option is only visible if the user’s “signed up trial?” field is false.
You could have a read of this too for more ideas of how to implement this: Subscription Based Web App