Hi there,
Ticket 42790637 states your contract has been nullified, so no you're not held into any 18 month contracts
Basically if you were one of the earlier triallists who got it for free, you'll be held to a contract if you upgrade. However if you joined later and were on the paid trial (which came with an 18 month contract I believe) the contract is written off when you upgrade.
Hope that clears things up.