The frist that should know users of obfuscation software: obfuscated assemblies still can be disassembled/decompiled.
The first target of obfuscation maximally complicate code and structure in assemblies to make reverse engineering really hard work that can take weeks or monthsto get really working source code.
Spices.Obfuscator provides protection from disassembling by the most of decompilers(including Spices.Decompiler) and ILDASM (MSIL Disassembler), provides a lot of different ways and levels of protection(not just simple obfuscation), but we can't guarantee that protected by Spices.Obfuscator code is 100% protected. We can provide you with recommendations that will help you to maximize protection of your code. By the way we're protecting Spices.Net assemblies by Spices.Obfuscator.
if suppose a dll is being obfuscated without spices.net,can the spices.net's decompiler work 100% after purchasing original version
It depends on level of obfuscation, if assembly completely obfuscated - Spices.Decompiler is able to generate source code, but it can take the time to manually restore obfuscated names of assembly members.