OK, so there are a few different answers to this… And remember, this is not CAN you do it, but rather SHOULD you do it.
Understand that having both ILM and NLS share the same IQ instance and database tightly couples your ERP and BW implementations.
At a high level, there is nothing preventing the combination of both ILM and NLS in the same IQ instance. Both ILM and NLS require standalone installations of IQ and configuration of the upstream product (Suite/BW). You would then create separate database connections and users for each archival method into the consolidated IQ instance. From a practical point, though, do you want to do this? I would not recommend combining the two use cases into a single IQ instance and database.
Combining both use cases can have a license impact that you may not be ready for. If you purchased the NLS option and the ILM option, you must have separate installations. The NLS IQ option gives you the right to deploy and use IQ for the SOLE purpose of BW. That means that the IQ instance licensed under the SAP NLS IQ option can only be loaded by BW and can only be queries via BW. The same is true of the ILM license.
As both the NLS and ILM IQ licenses are restricted use, any attempt to load ILM data into an NLS runtime licensed server would likely be a license violation.
The alternative is that you could purchase IQ Enterprise Edition (IQEE). In this case, the IQ instance is a full use license and you have the ability to use any means to load and query all your data.
As both systems are now sharing the same IQ instance, we have a tightly coupled ILM and NLS infrastructure. You cannot do a partial backup of an IQ instance. If you have IQEE and have both NLS and ILM data in the same server, you must perform a backup of all data. This presents quite some challenges as Suite and BW will archive data at different times. Additionally, they each have very different schedules for backing up the archived data. So, mixing the two archives into a single instance of IQ would lead some some very tricky integration needed between Suite and BW.
It is also prudent to mention that the systems can impact each others workload. Will the NLS use case slow down ILM? Will ILM slow down NLS? Likely not in either case as ILM is lightly used compared to NLS. But it is worth mentioning.
So yes, it could be done, but in reality you don’t want to do it. Licenses are the big prohibitor. Architecture and coordination would present some operational challenges that make it quite difficult.
If you’ve asked this question, I would want to dig further to understand the “why” behind it. Many times, this question is asked not because we really want to combine the systems, but more because we want to use the same hardware for both as they may be lightly used systems that could share compute and disk resources.
To answer the question of running both on the same system, I would recommend that we deploy two IQ installations on the same host; one for NLS and one for ILM. This allows each system to be treated separately, no more tight coupling, and allows you to use the proper licenses for the use case at hand.
In the end, there are both license and architecture obstacles to overcome by having both NLS and ILM share the same IQ instance and database. I cannot imagine a scenario where having both share the same IQ instance is beneficial.