Fiancé Purchasing Premiums

We have been together for 2 years and Recently engaged about a month ago. My fiancé admitted to me when we first started dating that he was purchasing Snapchat premiums but stopped when he met me. I’ve always trusted him but he has been using the restroom a lot lately. Like, abnormally often and I advised him to see his doctor but he refuses. So I decided to sneak on his phone for the first time while he slept and as guilty as I feel, I discovered that he is buying Snapchat premiums. There is also a lot of saved pictures and videos of other women in his snap conversations from these premiums. I feel so uncomfortable and insecure about this. This is literally the only thing I see wrong in our relationship and I don’t know if that is normal or not. I mean, it’s only Snapchat Premiums but I feel unappreciated and don’t know how to approach this. Have any of you experienced this or am I overthinking it?

Edit: Thank you for responding ladies. You all are so encouraging. A side note, I don’t care if he watches porn just because I felt it wasn’t as personal as premiums. But now I’m a little heated and am still thinking of ways to start this conversation.