The method is certainly free, it was developed by Frank Glahn at that time (80 years ago) and Doebereiner and Huber only adopted it. Almost all astro programs from Germany and Switzerland offer this method. But I think the terms are protected: "Münchner Rhythmenlehre, Huber Alterspunkt, Phänomenrhythmus, Weg der Aphrodite, Fügungsrhythmus, APL- Pyramidenen-Rhythmus" ... you have to be careful. Today everyone likes to sue everyone.
Here is a quote from Astrowiki: "Glahn, who studied English-language theosophical astrology extensively, adopted the seven-year period for the signs of the zodiac (7 years per sign of the zodiac) in his system of the circle of life. Engelhardt, the naturopath, who conducted courses on the Glahn method and also sent teaching letters, recommended using the seven-year period in addition to the Glahn period of 8.33 years per house (also based on the ascendant for seven years per house, houses according to Placidus) Rhythmisation) was taken up in Germany in the 1950s by Wolfgang Döbereiner's theory of rhythm in Munich and at the end of the 60s by the Huber School, which allows an age point to wander from the ascendant through the first house system. "
Source:
https://www.astro.com/astrowiki/de/Frank_Glahn