Hi there, @neongod.
I can see you need the custom field function in QuickBooks Online. I'm here to share details about upgrading your subscription while you're under the discounted plan.
We can no longer apply the discount if you upgrade or downgrade your account in QuickBooks Online. However, QuickBooks offers other discounted plans for our customers. Check out this page to see promos: Choose a QuickBooks plan.
I'm also adding this article to give insight into what will happen after canceling your subscription: Cancel your QuickBooks Online subscription or trial. It also provides steps to withdraw your account.
Furthermore, you can refer to this page if you're ready to upgrade or downgrade your subscription to QuickBooks Online. It also includes information on how to revert to your previous account.
We are open 24/7, @neongod. You can always post your concerns here in the Community forum. Keep safe.