Are you looking to upgrade from Trello Free to Business Class / Enterprise?
If yes, you can see the pricing for the two options on the pricing page - and from here access options to make payment for these services.
For more information on the different licenses, see this page
I'm not sure of the exact payment options for Trello - but if you wanted to pay via invoice or an option that isn't available, you could consider contacting an Atlassian Partner to see if they can assist with your payment method.
Hello Community! My name is Brittany Joiner and I am a Trello enthusiast and Atlassian Community Leader. I'll be sharing with you a series of videos with my top tips on how to best use Trello...
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