No. The law does not impose a maximum age for selling a life annuity; on the other hand, this sale supposes a hazard, based on the lifespan of the seller. If it is shown that the purchaser, when signing the contract, could not ignore the high probability of the near death of the seller, then the sale could be challenged legally by the latter's heirs.
In addition, article 1975 of the Civil Code provides that the life sale contract is void when the annuity was created in regard to a person suffering from the disease from which he died within twenty days of the date of the contract.