There is no need for you to renew your account manually. Any account which is still active on your renewal date will automatically renew. (This includes both monthly and yearly accounts.)
If you do not wish to renew your subscription at the end of the month or year, either close your account before its renewal date or contact Support at firstname.lastname@example.org.
You can close your account within the program or online by clicking on "Account" and then "Cancel Account."
Please keep in mind that unless your account is completely closed, you will be billed automatically. Uninstalling SpiderOak does not cancel your account.