Other effects may remove Keywords. 1. The effect that removed the Keyword will specify the duration it is removed. 2. If an effect that removes a Keyword does not specify a duration, the duration is as long as that Game Object remains on the Board or in its current Non-Board Zone.
§ 801.3.b Core Rules PDF (officieel)
§ 801 A Keyword is a specific term that appears on Cards that acts as a shorthand for a specific game effect, or ability of any variety.
§ 801.3 Keywords can be referenced or specified by other Game Effects.