Article in English: iTunes Match, a subscription that stores all of your music in iCloud and allows you to re-download deleted songs, costs $24.99 per year.  Open iTunes. Click the Store tab. Click the iTunes Match link on the right side. Click the blue Subscribe button. Enter your Apple ID information. Enter payment information if prompted. Click Subscribe If you didn't already open iTunes to sign up for an iTunes Match subscription, open it now. Click Account in the upper-left side of the iTunes window (Windows) or the screen (Mac), then look for your account name in the drop-down menu. If it isn't there, click Sign In... in the drop-down menu and enter your Apple ID credentials. In order to "convert" music from protected audio to MP3, you'll first need to delete the protected audio from your iTunes library. Keep in mind that this must be music that you purchased from iTunes. Click the song or album to select it, then press Del (Windows) or click Edit and then click Move to Trash (Mac). This will remove the protected audio file from your iTunes library. You'll find this on the right side of the window. If you purchased the song or album from iTunes, you should find it on this page. You can click the Not in My Library tab at the top of the window to show only purchased music that isn't in your iTunes library. You should see this cloud-shaped icon near the song or album; clicking it will prompt the unprotected version of the song or album to download onto your computer.

Summary in Vietnamese:
Bạn cần chắc chắn rằng mình có gói thuê bao iTunes Match. Mở iTunes. Bạn cần chắc chắn rằng mình đã đăng nhập. Tìm bài hát hoặc album mà bạn muốn chuyển đổi. Xóa bài hát hoặc album. Nhấp vào liên kết Purchased (Đã mua) nằm bên phải cửa sổ. Tìm bài hát hoặc album mà bạn đã xóa. Nhấp vào biểu tượng tải xuống "Download".