Echoing Sonnet,
There are definitely benefits and drawbacks to
Life Membership.
For me, the big personal benefit is the projected lifetime dues savings. Life Membership is a great gift to give to, or receive as, a newer library worker. The up-front cost was beyond my reach, until I received a lump sum (for incorrectly calculated back-pay) that I was able to apply to the payment.
For me, the personal drawback is that the smoother, online renewal process for my Divisions and RTs is not available and requires calling in (and, harder, to remember to call in).
Flipping perspectives to the budget side, Life Membership, while the right thing to offer members, effectively reduces long-term association income. After ~15 years (for new life members aged 45 or younger) each life membership reduces subsequent annual income by one base dues payment. Sure, my lump $2,000 from eight years ago was useful then, but now my life membership nets the current year budget a negative $150 in dues, compared to what I would contribute were I a paying personal member. (a "loss" that I offset with dues for 4 Divisions and I've lost count how many RTs)
Other than no longer paying annual ALA dues, I think there are no benefits for Life Members beyond the benefits that are avai;able to all ALA members.