Hi there Ten
Thats a good question and thanks for using QandAa platform
So answering to your question I guess yes you can use azure services for commercial usage. when you say related to costs if you have an account and you are paying for the azure services as long as you use them and pay them keep them active, you have no problem using those resources in any commercial projects.
If you are on free trial just keep in mind they will end soon, if so do upgrade your subscription,
Hope this clears if this helps kindly accept the answer thanks much.