We have modified the initial query and added the regkey fields from the second report to it. Hopefully this is the result that you are after.
Select Top 1000000 tblAssets.AssetID,
tblAssets.AssetName,
tblAssets.Domain,
tblAssets.Username,
tblAssets.Lastseen,
tblSoftwareUni.softwareName,
RegKey.RegKey,
RegKey.Valuename,
RegKey.Value
From tblAssets
Inner Join tblAssetCustom On tblAssets.AssetID = tblAssetCustom.AssetID
Inner Join tsysAssetTypes On tsysAssetTypes.AssetType = tblAssets.Assettype
Inner Join tblSoftware On tblAssets.AssetID = tblSoftware.AssetID
Inner Join tblSoftwareUni On tblSoftwareUni.SoftID = tblSoftware.softID
Left Join (Select Top 1000000 tblAssets.AssetID,
tblRegistry.Regkey As RegKey,
tblRegistry.Valuename As Valuename,
tblRegistry.Value As Value
From tblAssets
Inner Join tblRegistry On tblAssets.AssetID = tblRegistry.AssetID
Inner Join tblAssetCustom On tblAssets.AssetID = tblAssetCustom.AssetID
Inner Join tblState On tblState.State = tblAssetCustom.State
Where tblRegistry.Regkey Like '%_Px_Tools') As RegKey On tblAssets.AssetID =
RegKey.AssetID
Where tblSoftwareUni.softwareName Like '%Autodesk AutoCAD 2016%' And
tblAssetCustom.State = 1
Order By tblAssets.Domain,
tblAssets.AssetName,
tblSoftwareUni.softwareName