Apart from 90 days currency of the crew that must be monitored by operators (click here for more information, section 'Cockpit crew status') some operators have to track that the crew have flown at least once in the last 28 (Europe) or 30 (Asia) days - that includes 'Simulator' flights.
You can easily check if a particular crew member has flown in the required period of time by going to the section Crew Duties table and hover the mouse over the status-dot. Make sure that in the filter the checkbox '28 days currency (cockpit) is ticked (see below).
Leon will update 28/30 days currency if 1 of the below requirements is fulfilled:
On the screenshot below crew RYAN had flown his last flight on 25-03-2014. The date of checking the status is 04-04-2014. When hovering the mouse over the status-dot Leon shows the information, that 18 days left to expire the 28 days currency for the particular type of the aircraft.
When you add a training-type duty (defined in Crew Duties > CDR Definition section), i.e. SIM - Leon will also take this simulator-flight into overall 28 days currency calculation. The example below shows that crew RYAN had done SIM flight on 31-03-2014. The date of checking the status is 04-04-2014 - Leon shows that 24 days left to expire the 28 days currency.