If you are going to only need a one-time instrument currency session, book a three hour lesson.
However, if you are going to use the simulator with our instructors on recurrent bases to stay Instrument Current, you are better getting an annual membership.
The annual membership price was designed for pilots who are looking to stay instrument current. Instead of paying 3 hours every six months for an airplane and instructor, you can come in every 3 months for 3 hours and stay instrument current, which will save you time and money. If you are looking to stay instrument current with an airplane, considering rental fees, it would cost about the same to rent a C172 with a CFI.
Lesson scheduling is only available one month in advance. At the end of the month, our instructors get their airline schedules for the following month. Lesson availability is based around their flight schedules.