GST is not applicable (Subject to conditions below) :
As per Notification 12/2017 CT (r) if you are providing charitable services being mentioned in the Notification & not charging for the same , then membership or any donations received by trust is not taxable..
In Short GST is not applicable to donations/Membership made by a donor or member to a registered charitable trust, however, any fee charged by the trust from a beneficiary in exchange for goods or services will be taxable under GST.
Kindly Refer the Flyer on the same updated on CBIC site at the link https://goo.gl/EgAJtA.