The anti-Ahmadis raise an allegation on the book Nishan-e-Asmani, page 398:
They say that Hadrat Ahmad (as) says that since 1892, ten years of his prophetic mission duration have passed. Hadrat Ahmad (as) has never made any such prophecy and himself says Allah Knows best. He is only doing commentary on the poem of Shah Nimatullah Wali sahib. His prophecy is the prophecy of living around 80 years and this was fulfilled.
Secondly, in Tofha-e-Golarviyya Hadrat Ahmad (as) explains that he received revelation 35 years ago and that he received revelation at the age of 40. This gives us the age of 75 in 1902 and 81 in 1908. The Promised Messiah (as) fulfills 40 years of divine revelation if we count from his first revelation.