Can I subscribe to silver package and use it for two months only?

I have an events which  I need to register users atleast like 8000 people, however after this event I may not require to use this package. Can I pay for two months only or it has to be yearly?

No need to buy the yearly plan. You can subscribe to the monthly plan and cancel the subscription after the second automatic charge. The account will remain on Silver until the period you paid for expires.