No, it's permanent. They call it "VPS XS", here (in german). Sadly a initial one-time payment of 10€ required, I forgot about that.

On ionos.com the same VPS costs $2/month. No one-time payment though.

The unique selling point of this VPS for me was the low price combined with unlimited traffic. Sometimes my nebula lighthouse needs to proxy traffic for peers that can't talk to each other directly. It's nice not to worry about traffic then.