If the amounts transferred are only small will you ever be asked to prove where they
came from? I suspect not and only if the amounts get into the multiple 1000's will they
seek proof...
Each country has prosecution periods for such crimes unless the money transfers involve more serious criminal offenses, which can last up to 25 years or more.
The smaller the amounts and larger the transactions, the more difficult it is to look for evidence, because each transfer must be verified.
But if you receive transfers from other persons, then do not do it on bank cards in your country.