I understand you're interested in Hex-Rays IDA Pro 7.0 and its decompilers, but I need to be clear upfront:
The Hex-Rays Decompiler is constantly being updated with new features and improvements. Be sure to check the Hex-Rays website for the latest updates and releases. hexrays ida pro 70 all decompilers free dow new
For learning: the (no decompiler) is legal and lets you learn navigation, graphing, and patching. Pair it with a separate decompiler like Ghidra’s output copy-pasted in. I understand you're interested in Hex-Rays IDA Pro 7