If you edit the price of your subscription to a higher or lower amount in Thinkific, students who purchased before your price change will not be affected. Students already set up as subscribers will always pay the price set when they first subscribed. New students will pay the new price.
Note that this also applies to those students who are set up on payment plans.
If you want to adjust the pricing for existing students, check out: Can I update the subscription price for currently subscribed students?