The duration of a full membership will depend on how long it takes you to use your 24 appointment credits. For most people, a full membership will last six to eight months, but for some people the membership may take longer. Therefore, the membership doesn't end until you cancel it.
Only cancel a membership if you are sure you want to stop. Once you cancel, it may be difficult or even impossible to restart. Restarting presents the following issues:
All the slots may be taken.
There may be some slots available, but none of the slots work for you.
The price for a membership may have gone up.
There is a setup fee.