The International Tennis Federation says the ban expires Sept. 7, 2015.
The 33-year-old Llagostera Vives now plays only doubles, though her singles ranking reached No. 35 in June 2005.
The ITF says she was to have teamed with partner Francesca Schiavone at the Bank of the West Classic in Stanford, Calif., in July, but withdrew because the Italian was not well. The governing body says Llagostera Vives was still randomly selected for testing and could not explain how the drug entered her system.
The day before the doping test, Llagostera Vives had visited San Francisco but said she had "only consumed a bottle of water" while there, the ruling stated.
ITF expert witness Christiane Ayotte said the banned substance "was and is available only as a street drug (crystal meth or meth) or as a stimulant or as a party drug," except when prescribed for some behavioral disorders.
The ITF says Llagostera Vives retains prize money and ranking points in tournaments since July, including reaching the round of 16 at the U.S. Open while paired with Liezel Huber.