The pair were convicted of repeatedly abusing and raping the boy, now 10, and selling him to men on the darknet, an area of the internet that can be visited only by using special software. Her partner, Christian L., was sentenced to 12 years.
The 48-year-old woman and her 39-year-old partner were also convicted of repeatedly raping the boy, now 10, and filming the abuse.
She received a jail term of 12 and a half years, and the stepfather was sentenced to 12 years for the torment they put her son, aged nine at the time, through.
Lais, 39, had a previous conviction for child abuse, raising questions why he was allowed to live in a home with a child present. Some of the abuse was filmed.
Six other offenders have been handed lengthy prison sentences as part of the case.
Six other man were also given sentences for sexually abusing the young boy. It said the mother was aware from the start of the man's pedophile tendencies and previous conviction.
In May 2015, the couple started abusing the woman's son, with the man at first offering the child cash.
Video footage catalogued the horror of the boy's abuse, which included him being tied up and subjected to verbal humiliation.
The couple was also ordered to pay a total of €42,500 in damages to the boy and another victim, a girl who was temporarily in their care.
Local authorities have been accused of failing to protect the boy, who now lives with a foster family, as the mother's partner was supposed to be banned from having contact with children.
Katja Ravat, the child's lawyer, said the mother had not shown remorse at any point during trial, adding that she "had hoped that [the defendant] would make a statement, issue a written apology to her child, or at least explains to him why she did it".
The boy was taken out of the family home in March past year, but was sent back weeks later by a local court.