When you cancel your Sphere membership, you have until the end of the current term that you paid for to access your files.
There's no way to "pause" the membership and restart it again and have your files still be there.
After the membership ends, any files stored in the cloud will be deleted. You'll need to download all the files from your cloud site before the membership expires.
As you are the originator of the workspace, anyone who was invited will lose access to that workspace and any files on it.