Here’s my take on this.
I can see a couple of ways to approach it. Since you already have access to their phone, the most direct method is simply opening Snapchat and checking the Memories section yourself. This is straightforward and requires no extra software. The main drawback is that you have to physically have the phone and it’s a manual process, showing only what’s currently saved.
The other route is using a dedicated monitoring app. These services are designed to capture activity and send it to a dashboard you can view remotely. The benefit is convenience and automation. However, their ability to capture everything within a specific app like Snapchat can be hit-or-miss, especially with newer Android versions. It really comes down to choosing between direct manual access and the features of a third-party service.