All perfect praise be to Allah, The Lord of the Worlds, and may His peace and blessings be upon our Prophet Muhammad and upon all his family and companions.
It is permissible for a Muslim to use beads as a means of counting Tasbih, Dhikr, and Istigfar since many a narration was reported after the righteous companions and their followers showing that beads made of dates were used for that end.
Not only are beads a lawful means of worship, it was also confirmed that the Prophet (PBUH) counted Tasbih upon his fingertips. This indicates their permissibility as they aid a Muslim in keeping count of Tasbih. Therefore, it isn`t permissible to claim that they are innovative since none of the Muslim scholars have said so.
About this matter, Al-Saiouti has written a paper entitled [Al-Menhah Fi Al-Sibhah] which is included in the book [Al-Hawee Lil Fatawee,vol.2/pp.4-6].
Ibn Hajar was asked: is there an evidence in Sunnah for its permissibility? He replied: yes, and al-Saiouti has written a book about that. One evidence is what Ibn Omar (May Allah be pleased with both of them) reported about having seen the Prophet (PBUH) counting Tasbih upon his fingertips. Moreover, Humaidah bint Yasir narrated from her grandmother Yusairah - and she was one of those who emigrated - she said: “The Messenger of Allah (PBUH) said to us: ‘Hold fast to At-Tasbih, At-Tahlil, and At-Taqdis, and count them upon the fingertips, for indeed they shall be questioned, and they will be made to speak. And do not become heedless, so that you forget about the Mercy (of Allah).” {At-Tirmizi}. In addition, some of the Prophet`s companions and those who came after them were reported to have used pebbles, dates, and knotted strings as means of counting Tasbih. Moreover, it was related that some scholars said: "Counting Tasbih using fingertips is better than using beads, based on the narration of Ibn Omar." Some of them even gave details where they said: " If the person saying Tasbih is certain about his count then it is better to use his fingertips, but if he isn`t then it is better that he uses beads" {Al-Fatawa al-Fiqhiah al-Kobra,vol.1/pp.152}. And Allah Knows Best.