Only techniques such as electrolysis can make this claim. The possibility of permanent hair removal can also be claimed by techniques such as laser/IPL treatments however it cannot be guaranteed. Permanence is suggested and the Advertising Standards Agency when anyone is claiming permanent hair removal.
Electrolysis can be associated as a permanent form of hair removal. We don't know anyone who would choose it as the depilation method of choice in anything but white/grey hair where laser/IPL won't work and that is because laser/IPL devices have developed and improved hugely in the last decade, but the effectiveness is yet to improve with its popularity.
Despite the claim from laser/IPL treatment administrators, the number of treatments that will be required is still almost impossible to predict. The number of factors to determine how many treatments any individual will need is too difficult to determine without a thorough examination.
Several treatments are still necessary to get a better idea of the total treatments necessary as it is still not easy to judge even after one or two sessions.
Realistically the customer will be committing to a course of 6 or more sessions before it will be possible to give an estimate to a number of treatments required. It is just as important to make sure to make the right decision as to who carries out these treatments as a considerable amount of money will have been spent before the customer even knows how effectively it has been spent.