Society charging for sale of Tenancy rights

We have a tenement which is rented by us as tenants since late 1930s. The housing society which was formed in 1941 has claimed to have ownership of the land on which the tenement is built and we are paying rent plus municipal taxes to this society (purported to be the landlord). However, the society does not take care of any structural repairs and maintenance of the tenement. The tenants incur all the costs for any structural repairs and maintenance. The tenancy rights have been transferred from my late grandfather to my late father (in 1982) and now to my mother (as recent as in 2015). We do not reside at the tenement since 2003, however we have been paying the rent properly and getting the receipts from the society and continue to do so. There does not seem to be any tenancy agreement document between the society and us. Also, i understand that since last two years (2014 onwards), the society has imposed a rule that the tenant cannot rent the tenement to any third party tenant but the tenant is allowed to sell the tenancy rights. However, another rule imposed is that if the tenant has to SELL the tenancy rights to any third party for a consideration, the tenant needs to pay 40% of such sale consideration to the society in lieu of their ‘No objection’ to the sale of tenancy rights. My queries are - 1) Whether the society can legally impose such rule on charging part of tenancy sale consideration in lieu of their no objection certificate? 2) What legal rights do we as tenants have in case of no signed agreement with the society except for the rent receipts for the rentals and taxes paid by us? 3) In above circumstances, do we tenants have absolute legal right to sell the tenancy rights to a third party without requirement of any permissions from the society?