I typed, "it lasted three hours" which was accepted with the comment that I had a typo and suggested "Its lasted three hours." The word its without an apostrophe is a possessive pronoun. I don't see how the Czech sentence has that meaning. I think my suggestion should not have been accepted because I used the past tense. I should have said, "It lasts three hours." In past tense it could be "It's lasted three hours." Am I missing something here? I reported this under the last option which is something like "other".
Trvá is present tense. "It lasts three hours" (simple present) and "It has lasted three hours" (present perfect) are among the accepted translations, as is "It's lasted three hours." I cannot explain why Duo offered a correction that did not include the apostrophe in "It's," as we do not control that. But look at the bright side -- your answer was accepted. :-)