Vaccines don't actually protect you against the virus, they just activate your immune system (your body's natural protection). Guess what else also activates the immune system? The actual virus!
At the beginning of the pandemic, there was some talk that anti-bodies might not last longer than 3 months, but that was obviously just FUD (there was literally no data). I had antibodies 6 months after being infected. Two additional things I heard (but don't have the source), your body can restart production of antibodies (B-cells remember), and people had SARS(-CoV-1) antibodies years after infection.
Finally, this: https://www.ft.com/content/929ef3cd-8611-49b2-9f23-918dc3470... Covid infection shown to provide as much immunity as vaccines - I haven't checked the source but FT isn't really known for fake news.
Are there any credible studies that say that infection doesn't confer immunity?