You might be interested in this: https://www.iamwmc.com/competition/training.html
Memory League is only about USD $2/month though. It’s a great deal for what it offers. Take a look at MemorysportsTV to see what people are doing with it.
People have been training memory for thousands of years, long before computers. Check out some of these books for ideas on how to train without spending any money (beyond the books themselves). Memory Craft is an especially good one. This site also has thousands of pages of free content.