Can a 3 month free trial be converted to a standard paid subscription or do I have to re-deploy

Can a 3 month free trial be converted to a standard paid subscription or do I have to re-deploy? Also, if it can be converted, can it be converted to a 6-month plan?

After the 90 days your account will be converted to pay-as-you-go automatically, you don't need to do anything. If you want to convert it to a regular pay-as-you-go just remove the price cap.

About convention to 6-month plan I think that you can't but you can contact billing support about that https:-//www.windowsazure.-com/en-us/support/contact/