we are using Aspose.Cells 5.1.0.0. and getting the following error
system error: you are using an evaluation copy and have opened files exceeding limitation
License is proper. can you please let me know which versions of excel is supported by “Aspose.Cells 5.1.0.0” can Aspose.Cells 5.1.0.0 supports 2012,2016 or 360.
I guess your licensing code is not processed in your application life cycle, so you should debug your application on your end and check if your licensing code (that refers to your existing license file) is executing properly at the start (of your application) before using any other APIs of Aspose.Cells. For your information, in evaluation mode (without setting a valid license in your code), you cannot load/save more than 100 files at a time.
Regarding your other concerns, Well, since you are using older version of Aspose.Cells for .NET (i.e., Aspose.Cells for .NET v5.1.0), it might have limitations regarding some features which are supported in newer MS Excel versions, e.g MS Excel 2013 or 2016 or others etc. when loading/saving to Excel files format. But it should work fine with MS Excel file formats, e.g XLS, XLSX, XLSM, XLTX, CSV, Tab Delimited, ODS, SpreadsheetML, etc. (MS Excel 97 - 2007/2010). We highly recommend to upgrade to latest Aspose.Cells APIs, so you should not have any problems with the files (loading, manipulating, saving) created in newer versions of MS Excel (2013, 2016).
Is there any restrictions of Aspose.Cells 5.1.0.0, due to that we can get the following error "system error: you are using an evaluation copy and have opened files exceeding limitation"
Well, there is no such restriction on Aspose.Cells part when you use and set a valid license in the code. Moreover, the code should be processed at least one time before using/processing any other APIs of Aspose.Cells. As I told you before, I suspect your licensing code is not processed in your application life cycle, so you should debug your application on your end and check if your licensing code (that refers to your existing license file) is executing properly at the start (of your application) before using any other APIs of Aspose.Cells, you may set breakpoints in VS.NET on licensing code segment etc.
Well, I think the issue may not be related to Aspose.Cells APIs by any means. As I told you the licensing code should be processed at least one time in the whole application life cycle before using/processing any other APIs of Aspose.Cells. I still suspect your licensing code is not processing at all in your application, so you should check your application (on how do you set your license) and debug your application on your end. Moreover, you might be using Aspose.Cells in multi-threading application so you got to make sure your licensing code is properly placed and processed (you got to check your logic for the placement of licensing code in your application). If you still think it is an issue with the product, kindly do create a simple application (runnable), zip the project and post us here (please do not include your license file rather send the license file via email, check this) to reproduce the issue on our end, we will check it soon.