Older events in sentry

Hi ,
Quick understanding on sentry. How are older events handled, like we have frequency of events for one type of exception to 35,270 on a day. Am just concerned here, stats shows last 14days charts.
Some where i see this exception is 4 months old.

How are older events handled by sentry,
What is the ideal way of looking into it?

Currently we have got huge box added for sentry which is costing more for us.
Looking into in cost, maintenance, cleanups?
Please suggest the best approaches for the same.