If you don't have a Jamworks account...
Head to https://app.jamworks.com/auth/registration to register for a Jamworks account. You only need to enter your email, create a password and add a first and last name to create an account.
Once you've created your account, you will see a selection of Jamworks plans. At the bottom of this page, you'll be able to input the licence key you were given to activate your Jamworks subscription:
Once the key has been redeemed successfully, your subscription will be active.
If you already have a Jamworks account...
Login to your account at https://app.jamworks.com/auth/login
Once you're logged in, click on your profile in the top right hand corner of the screen
From your profile select "Review & Upgrade plan"
Here you can enter your licence key to activate your Jamworks subscription.