I purchased Lifetime, and I don’t regret it, but I had a few considerations when I did:
- Needing a service which took care of a lot of the SRS details for me with minimal fiddling.
- Willingness to pay money at the time.
- Wanting to support the site, as it’s a useful service.
- Uncertainty as to whether I could keep my kanji learning going at full speed from start to finish.
As it turns out, I burned out on level 24, and stopped using WK for a while. I was able to pick it up a year later, as well as take my time to finish. Having a lifetime subscription meant peace of mind in that regard.
However, there are other ways to learn Kanji that cost less money. If you’re willing to do a combination of: getting other books, making mnemonics yourself, using Anki/other flash card apps, using Memrise, or who knows what else, you’ll pay less money at the expense of doing more work.
Also bear in mind that upgrades are prorated. If you want to keep paying monthly/annually and upgrade to lifetime later, you’ll be discounted whatever you payed on the lifetime of your account. This is a super good deal if you want lifetime and you buy in on a sale.