Enid Hardes, aged 73, is last known to have been in the town centre area at around 9.30am on Tuesday 1 June 2021.
She is described as being of average height, medium build and with greying light brown hair.
It is not known what Enid was wearing when she went missing.
Inspector Greg McNeil said: ‘The photograph of Enid is a few years old and her hair is more grey than shown.
‘We are very concerned for her welfare. It is understood she may have been in the High Street during the afternoon and we are urging anybody who sees her or knows where she might be to contact us.’
Anyone with information is asked to call Kent Police on 999 quoting 1-1560.