In business when you buy a product, many times you find that the definition of a lifetime is expressed in a fixed amount of years. Look at your ginsu knives
Personally though the cost of membership and the cost of the magazine are considered one and the same when ones dues are paid, perhaps they should be looked at seperately.
I don't mean that they shouldn't be purchased together but it should be understood that as costs rise in printing and mailing that lifetime members should expect the cost issue to be visited every 5 years or so and to expect an assessment to cover rising costs.

Of course another view would be to have the club lick its wounds and no longer offer lifetime membership.
I think at one point when interest rates were higher and the club was able to at least break even, there were no complaints. In reality there shouldn't be any now.

Perhaps offer a so called lifetime membership based on 20 years and when that time came to pass allow those that want to continue their membership at that point to be able to purchase continued membership at a reduced rate yet still based on current costs.
Let's face it, since lifetime dues were raised a few years ago, I doubt that many new members opted to become LM.
Increasing the cost will not help.

I think also one might consider what I'll call Junior lifetime mebership that will allow someone to sign up siblings up to a certain age lets say 18 with just the cost of membership not to include the club magazine.
That might get more younger members without having to bear the cost of the magazine.
Once reaching that age they would be required to pay full dues and get the club magazine

I think it has been known for years that the club magazine has been a losing proposition from the financial aspect of it. Now that it is becoming more serious, those that opted for lifetime membership should not be punished.
I will remind you that I am NOT a lifetime member thusly this is just what I feel, it is my impartial opinion