Firstly, it's great that you're looking to upgrade.
Secondly, you will NOT lose any free days of your trial. If you decide to upgrade before your trial ends we'll simply hold that information until the day you need to upgrade.
On the day after your trial ends we'll charge the card you've added and you'll have seamless access to the platform. By providing it early there's no risk of having access restricted once your trial ends.
The Fitr Team