To set a subscription price for your content: Go to Media Hub - Edit Profile - Set up Subscription
As a Creator, you are free to choose how much you charge for your services.
Your pricing can heavily influence the number of purchases. Generally, we see that cheaper pricing converts better, but it's up to you to find your sweet spot.
When you raise your subscription price, all new subscribers will be billed at the new rate. Keep in mind that your existing subscribers will continue to be billed at the original rate they agreed to pay when subscribing to your profile.