I'm in my 60s, and new to diarium, but I have several uses planned:
1) A standard journal - thoughts, emotions, events, reflections going forward.
2) Digitising my old paper notebooks. I tend only to journal at times of stress or change, and when I'm travelling. I plan to photograph pages from the old journals, add them to the relevant date, then read them out loud and have the phone transcribe them.
3) Consolidating Family History. Some years ago my father made a doc with a timeline of major events and dates in his life. My sister and I did something similar. I can transfer those entries into my Diarium as well.
4) Memoirs. That's a pretentious word but as I get older I wish someone had written down the stories and memories my parents shared. Now when those stories surface in my brain I'll have somewhere quick and easy to store them.
At some point in the future I may export and print some of this.