What I've been told so far is that Babbel and Duolingo (when it still was great) are mainly toys to keep ones motivation up but are less helpful for actually learning the language.
For that I was mainly pointed at Rosetta Stone.
But coming back to your question, when you're actually using it and you plan on using it for at least the next two years then you should get it.
(Don't expect it to actually last a lifetime though)
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