Send them a formal letter reminding them that the Intellectual Property is yours. If they have any investors, you might want to copy them on that letter too.
Regarding the government compliance, I think it's safer to err on the side of the law than on the side of someone who is only promising future rewards, with no commitment on their part.
If you're in a different country than the company, it may be hard (and costly) to assert your rights, so keep that in mind: it's a liability for you to do too much for free. You're basicaly extending them a line of credit hoping to be paid back but with a non-certain process to recover your investment if they don't stay true to their word.
Regarding the government compliance, I think it's safer to err on the side of the law than on the side of someone who is only promising future rewards, with no commitment on their part.
If you're in a different country than the company, it may be hard (and costly) to assert your rights, so keep that in mind: it's a liability for you to do too much for free. You're basicaly extending them a line of credit hoping to be paid back but with a non-certain process to recover your investment if they don't stay true to their word.