You may reactivate your membership at anytime and No you do not need to pay previous years membership.
You are not required to be an Individual Membership to attain or keep your certificate. If you do not renew as an Individual Member, your Membership will be downgraded to Affiliate Status, which is free. If your Membership is set to Auto Renew you need to e mail a request to disable that renewal to Membership@garp.com. If your Membership has auto renewed in the last 60 days and you wish to have the $150 membership fee refunded, please e mail that request to Membership@garp.com
Global Association of Risk Professionals (GARP)