Antibodies are relatively short lived, but memory T cells and B cells (ready to make more antibodies on new exposure) can last decades.

Immunological memory to SARS-CoV-2 assessed for greater than six months after infection

https://www.biorxiv.org/content/10.1101/2020.11.15.383323v1

I’ll take the vaccine as soon as it is available. 95% reduction in risk without significant side effects in 20,000 trial participants is far better than I had dared to hope.