iCloud and itunes un Iphone

I buy music from iTunes in my iPhone and deleted them as soon as the download is completed. All of my music in my iPhone plays from the cloud.

I thought that by using the cloud, I was going to save memory in my phone but I noticed the space use for iTunes is 1GB.

Am I doing something wrong? How can I save space in my iPhone when I buy music?

Please help,

Juan Sevilla