How to upgrade to a paid plan
So great to see you'd like to move to a paid plan!
If you're wanting to track more than 5 groups, all you need to do to upgrade is add in your billing information via the billing page. You can get there (as an account admin) by clicking on the gear icon in the top right > billing.
Once you add your billing info, then you can add more active groups and make any inactive ones active. You'll be charged at the end of your billing cycle (every 30 days, since the day you created your account), based upon the number of active groups you have and which plan you fall under.