L1A Individual Visa to H4

My L1A Individual visa is expiring on April 30th 2015,but I 94 is valid till December 2017. Please confirm :

If I can stay in US till December 2017 without applying for an extension just like we can in case of blanket L1A visa . Or, I must apply the extension before April 30thOr, if I don’t apply the extension, I can still stay in US till I 94 expires but cannot work.Appreciate your help.