Apple Music Offline Playback Question

I've got a friend that is going on a cruise for five days but she doesn't want to pay for Wi-Fi access because she doesn't plan to use it much. Although, she does want to have music to listen to. I suggested subscribing to Apple Music for a month, uploading her ripped music in iTunes. Then she can download those songs as well as any others from Apple Music to her phone. My question is: Does the app have to check in at some point to make sure the user is still subscribed so that offline playback can continue? I put my iPhone in airplane mode and it played back songs I downloaded just fine. She won't have cellular or wifi access at all. At some point during those five days, will the app want to check online to see if she's still subscribed? I wouldn't want her to go through the trouble of subscribing, uploading and downloading only for the app to give a pop up asking her to connect to Wi-Fi in order to playback her downloaded music.