Dr Allan, who will celebrate his 95th birthday in April, is the Honorary President of Banff & Macduff SNP Branch and was a former Grampian Regional councillor, taking the formerly solid-Conservative seat in a sensational victory for the SNP in 1986 and holding it until Grampian Regional Council was abolished in 1996.
Commenting, Banffshire & Buchan Coast MSP Stewart Stevenson said:
"It is fitting that Norman Allan receives life membership of the SNP.
"It is not simply that he remains an inspiration to many generations of activists who have followed him, but also his significant public service as a Councillor and physician.
"In his 90s he has continued to campaign with a vigour that shows people a fifth his age how it can be done.
"And ultimately his innate good manners and politeness mean that he has a wide circle of admirers well beyond the party he has served with such distinction."
"It is not simply that he remains an inspiration to many generations of activists who have followed him, but also his significant public service as a Councillor and physician.
"In his 90s he has continued to campaign with a vigour that shows people a fifth his age how it can be done.
"And ultimately his innate good manners and politeness mean that he has a wide circle of admirers well beyond the party he has served with such distinction."