Your limit is at least $2,500 in a 12-month period. This applies to regulation* crowdfunding platforms.
Regulations established by FINRA limit the amount that individual investors may invest across all regulation crowdfunding platforms in a 12-month period, not only the amount on Mainvest. Because Mainvest does not know how much you have invested on other platforms, it is your responsibility to ensure compliance with these regulations.
The maximum amount you can invest in all Title III offerings during any period of 12 months is:
If your annual income or net worth is less than $124,000, you may invest the greater of:
$2,500; or 5% of the greater of your annual income or net worth.
If your annual income and net worth are both at least $124,000, you can invest:
10% of the greater of your annual income or net worth.
If you are an "Accredited Investor" you do not have a limit on what you may invest.
These limits are adjusted periodically by the SEC, based on inflation.
You and your spouse may combine your incomes and assets for purposes of determining how much you may invest, although if you do so, you will be treated as a single investor for purposes of determining how much either of you may invest.
*Kickstarter, IndieGogo, Patreon, GoFundMe, Robin Hood, E-Trade, Wealthfront, and Betterment are not regulation crowdfunding platforms.