Once you've created a group, you can upgrade members to Are.na Premium from your billing page:
1. Go to your billing page at https://www.are.na/settings/group_billing
2. Scroll down to your group and select either yearly or monthly Premium.
3. Click change selected members to choose which group members you'd like to upgrade. The total price will update as you go. Confirm the selection by clicking Done.
4. Add your credit card information and a coupon code if you have one.
5. Click activate to confirm your purchase. You're all set!
Please note: you must be the group admin (i.e., the creator of the group) to upgrade members. If you're not the admin, you'll need to ask your admin to handle billing or create a new group.