Why am I being charged on the very first day of Bluemix trial?

i signed up bluemix, so i am on trial account I have started learning Kitura along the tutorial https://developer.ibm.com/swift/2016/07/06/tutorial-deploying-a-swift-to-do-list-app-to-the-cloud/#comment-2218

I uploaded the files a several time to make the server run (actually the tutorial gave me wrong link for the files) now it works.

but I saw my Runtime Cost is $289.

I have not added any support plan although I have not put my credit card info yet, is that what is going to be charged after Trial or for every month ? Why am I being charged anyway? nearly $300 is too high for testing a server. Would you explain about the Runtime Cost that I am currently being charged please?

Bluemix provides you with a cost calculator that allows you to trace what you will pay for services, containers, and VMs. In your case since you have a trial account, that is only an estimate of what you should pay.