Bib Fortuna became aware of Spijek's true purpose in the Palace after witnessing Tanus assist Geezum in making a desert and showing absolutely no shakes or other symptoms of a recovering addict while working with whipped cream.
In exchange for not blowing Spijek's cover, Fortuna signed him on as a member of his man-harem. He often made Tanus perform the Truffle-Shuffle.
After Skywalker was satisfied with the information gathered by Spijek, he sent his team into the Palace with everything apparently going to plan all the way to the point where Luke blew everyone up in the Sail Barge. Unfortunately, everyone forgot to tell Tanus that part of the plan and he too was killed in the Skirmish At Carkoon.
When Luke handed in his report on the Jabba operation, he was sure to give Spijek a commendation for his actions undercover. He recommended that Tanus receive the Medal of Merit, but this was denied by Mon Mothma. "Meh," she said, "Win some, lose some."