curl --request POST \
--url https://api.helicone.ai/v1/stripe/subscription/existing-customer/upgrade-to-pro \
--header 'Content-Type: application/json' \
--header 'authorization: <api-key>' \
--data '{
"addons": {
"evals": true,
"experiments": true,
"prompts": true,
"alerts": true
},
"seats": 123,
"ui_mode": "embedded"
}'