keep the memebership, don't bother with insurance
I am NOT an insurance guru and I do not know about any but the "professional" insurance I carry through the PADI relationship so please take this with those caveats.
My professional insurance policy is a "claims made" policy which means that it covers me for "claims made" during the time the policy is in force (i.e., July 1 through June 30). This is unlike my car insurance, for example, which covers me for incidents that occurred during the time the policy was in force REGARDLESS OF WHEN the claim is made. The difference is that the "claims made" policy has "no tail" whereas my auto liability policy does have "a tail."
IF you have ever acted professionally, then you may well want to either keep your existing policy in force OR, if you have quit, you may well want to buy a "tail policy" which will cover you for claims which may yet occur for actions you did in the past.
Most US jurisdictions have a statute of limitations for torts of 3 years (the exact number will/may vary) from the date of the act -- EXCEPT for minors which is often 1 year after reaching maturity (generally 18). So, for example, you worked with a 10 year old kid and something happened, he'd have 9 years to decide to sue for his "trauma" as a result of corking and blowing his eardrum.
Something you may want to consider before you decide that insurance isn't necessary since you aren't working as a professional any more.
Re the "insta-buddy" issue. Your normal personal liability insurance either from your home owner's or renter's policy, should cover that -- and those policies generally have tails.
But why would you trust me? -- I'm just a figment of your electrons and I didn't stay in a Holidy Inn Express last night!