This means that if you are currently using Informix 11.70, then after 30 September 2020 you will not be able to receive technical support for this product from IBM. It will not affect you entitlement to use the product.
If you have active maintenance subscription and you are able to upgrade to a more recent, supported version of the product then we would recommend upgrading to version 14.10. IBM has already stated that the preferred replacement version is Informix 14.10.
If you are not able to upgrade before the deadline and you need technical assistance please contact us for advice.