There is no ancient text that names a thirteen-circle figure the Fruit of Life. The term belongs to the modern sacred-geometry literature, where it fills a specific structural role: it is the step that converts a pattern of circles into a set of points, allowing the sequence to continue into straight-line figures and from there into three dimensions. Circle and vesica piscis, then Seed, Flower, Fruit, Metatron's Cube, then the Platonic solids, that chain is a teaching device of the last few decades, developed and spread largely through the workshops and books of Drunvalo Melchizedek from the mid-1980s onward.
Saying so is not a dismissal of the geometry. Every step in the chain is constructible with compass and straightedge, and each step does what is claimed of it in strictly geometric terms. The thirteen centres really do generate Metatron's Cube. What is modern is the framing: the idea that this is a single revealed progression describing how creation unfolds, and that the ancients knew it in this form and under these names.
The number thirteen attracts attachments of its own: thirteen lunar months in a year, twelve disciples around Christ, twelve around one in a range of traditions. These are correspondences drawn after the fact. Twelve circles surround one because six fit in a ring and six more fit beyond them in hexagonal packing, and the count would be identical whatever anyone believed about it. A number that falls out of the geometry cannot also be evidence for the meaning read into the geometry.