When your IMI maintenance expires, your existing IMI installation will remain fully functional.
The customer obtains an IMI maintenance and installs UMS 5.01.100 with IMI V1. During the maintenance period IGEL releases UMS 5.04.100 with IMI V2, which the customer can install and use. After the maintenance expires, UMS 5.07.100 is released. Now the customer can continue using IMI V1 and V2, but they cannot install IMI V3, as it was released after the maintenance period.