Replied 10 September 2017, 10:59 am EST
I am not able to replicate this issue at my end.
1. Visual Studio will require the Spread dlls to be present with the user control and also the machine should have a valid license. Then you can work with user control created with Spread at design time.
2. The reason is stated that you need to include the Licenses.licx file in your project when creating the user control. In case you have a licenses.licx file added already , please make sure that the version number mentioned for Spread in it same as shown by the dll in references.
I tested this issue at my by creating a user control and using this user control both in licensed and unlicensed machine.
a. On unlicensed machine it shows the license error design time(but not the licenses.licx error) and works fine at run time.
b. On licensed machine the user control works fine both at run time and design time.
Please refer to the attached images.
Hope it helps.
P.S. You can add the run time license by running the license activation tool from "Tools" menu in Visual Studio.