Every January a substantial sum of money (roughly third of a month's take home pay) leaves my bank account and finds its way to various professional and learned bodies. The bulk of this relates to my registration as a chartered engineer and appropriate bodies, which allows me to continue to use, should I so wish, the letters after my name. Pretty much every year I debate the continued expenditure, since I don't practice as an engineer and the last CPD I can reasonably claim was more than a decade ago. The various bodies, of course, are happy to take my money and not ask for evidence of CPD; indeed one of them from time to time writes inviting me to up my status from 'member' to 'fellow' - an invitation I studiously ignore, I would not qualify. But every now and then, having those letters comes in useful, giving credibility to responses I give to insurers or architects or contractors - I may not practice as an engineer, but I do retain the ability to speak the lingo, to make reasonable judgement calls on reports, documents and, very occasionally, to write responses in a competent fashion.
The remainder of the money pays for continued membership of Baptist groups, one effectively a 'learned society' and the other purporting to be a 'professional body'. From time to time I consider adding other minister-type subscriptions, but given that I rarely do more than glance at the four journals I receive (two minister, two engineering) would it be justified?
At the end of the day, the cost of these assorted memberships amounts to a little over £1 a day, which compared with my other expenses is pretty minimal. It is rare that I use my 'letters', but at this price, and with the continued, if infrequent call on my professional judgement, it is probably money well spent.