The Winter War on here is a common topic. However this question is not about the war itself, rather what were the postwar ramifications for Finland as a result of their participation on the side of the Axis?
Hi, I answered essentially the same question earlier here:
The TL;DR version is that the United States, which was the only power Stalin listened to, considered Finland's case differed from the other Axis allies enough so that Finland shouldn't suffer any "extra" penalties aside from losing the most productive 10% of her lands. Stalin let Finland stay democratic with the proviso that Finnish policy would not endanger Soviet interests, but extracted very hefty war reparations nevertheless.
Related question about post-war Finland: is the assumption true that Finland managed to avoid Soviet geopolitical influence/interference unlike most Eastern European countries after WW2?