Hey Wale Azeez
Thats a great question and thanks for posting it on QandA platform.
So typically, when you upgrade from a free trial subscription to a pay-as-you-go subscription in Azure, you won't forfeit any remaining free credit. The unused portion of your free trial credit should be carried over to your pay-as-you-go subscription.
You can learn about about this in the documentation link lemme give provide it below
https://learn.microsoft.com/en-us/azure/cost-management-billing/manage/upgrade-azure-subscription
If this helps kindly accept the answer thanks much.