On June 1st, EOS tokens will be frozen
On June 1st, 2018 Block.one, the company behind EOS, will distribute the last block of EOS tokens. On that day at 22:59:59 UTC, all EOS Tokens will become fixed (ie. frozen) and will be non-transferrable on the Ethereum blockchain. Before that happens, you can either exchange your EOS Tokens for another cryptocurrency or wait until a new blockchain is created.