What to record for every credit
Whatever system you use, each entry needs the same fields, because they're the fields an audit asks for: the activity title, the provider, the date, the duration or credit value, which certification(s) it counts toward, and a link or note that proves it happened. Capture these at the moment you finish the activity — reconstructing them months later, from a calendar invite and a fuzzy memory, is how credits quietly fall through.
If an activity counts toward more than one certification, record how you're allocating it. Some bodies expect the same activity logged in each portal; double-counting within a single certification, on the other hand, is exactly what audits look for.