I know exactly what you mean. My wife and I joined as lifetime members several years ago yet I still regularly get correspondence from the alumni association asking me to pay and join it again. If they can't even keep up with who the lifetime donors are, it makes me wonder how the donations that come in are managed.
Same thing happened to me and my wife. We joined the LA Tech Alumni Association and bought a lifetime membership about 30 years ago, and they still call me and tell me we're not members. It's insulting, and I refuse to do it again.