I suspect that the $99 package you purchased last year was a special promo.
As for where to purchase it again, you should be able to renew your
subscription from within the payroll module. Open the Payroll center and
go to the Payroll tab. Under Subscription Statuses there will be a link
for "manage Account". You should see that the subscription will be
automatically renewed and charged to the credit card listed on that screen.