These light and cheap absorber panels can help quickly optimising a space. they work well in small spaces, eg directly behind a speaker that is against the wall to alleviate those immediate reflections a bit, and because they are so light you can quickly put them on problem surfaces, even on just tape.
I work sometimes in temporary ateliers, and these are great for that purpose. My oldest of these are about 10 years old, and they are still ok, but they lived a lot of those 10 years in a box, without sunlight or UV radiation hitting them. UV radiatioin can destroy the foam over time. It becomes brittle, non-spongy and disintegrates into a dust that becomes a sticky mess after applying pressure to it. Estimated life span of these kind of acoustic panels is 7 years in a clean studio.
I recently took over a studio that had similar panels to these. Over time (well, it was 20 years), they had fallen apart, the floor had become a sticky mess and the dust started roaming the place. I replaced them all with other options that have an expected life span of 80 years.
While one would not expect these things to last decades, for just a little bit more money you can make some DIY panels from rockwool and cloth, which will easily last 20 years, or buy some more expensive and better options. (you don't want this dust in your speakers, instruments or lungs)
So in conclusion: these work ok as a quick stop gap measure, and can really help in temporary occupied spaces. But if you're having anything more permanent, I' d look into other options.
