Saver memberships, previously called fixed-term, can be purchased for a one-off payment for a set period. Saver memberships are different at each gym and you can view this on your preferred gyms' page here
To purchase this membership, you will make a one-off payment at the point of purchase that is the cost of the duration upfront. This often saves you money in the long run and allows for better budgeting as the money has come out upfront.
For more information on memberships, click here.